(New York-centric page by Stuart Frankel—please send me corrections or additions.)
Chinese and Indian stores are numerous. Here are some stores that specialize in SE Asian food:
Asia Market Corporation. 71 1/2 Mulberry Street, New York, NY 10013. (212) 962–2028 / (212) 962–2020
A well-stocked store especially for Indonesian and Phillipine groceries. Has a few cooking implements such as lempers from time to time.
Bangkok Center Grocery. 104 Mosco St, New York, NY 10013. Phone: (212) 732–8916
(Mosco is that little street that slopes down from Mott to Mulberry between Pell and Chatham Square.) A wonderful store which imports and carries exclusively Thai products. A reliable source for fresh kemangi or closely related herbs, and an excellent selection of frozen vegetables and fruits, among other things.
Udom's Thai and Indonesian Groceries. 81 Bayard St, New York, NY 10013. (212) 349–7662
A very small store (but ask for what you want) run by a gentleman from Thailand and his Indonesian (Chinese peranakan?) wife.
Top Line Supermarket. 81–37 Broadway, Elmhurst, NY 11373. (718) 458–5505
A large (by New York standards), well-stocked supermarket, including a nice selection of fresh produce and fish. One aisle is dedicated to Indonesian products.
Asian Food Inc. 2301 University Blvd W, Wheaton, MD 20902. (301) 933–6071
Mainly Thai foods but also many Indonesian products. The Thai lunch counter is worth checking out, too.
Thai Derm Restaurant. 939 Bonifant St, Silver Spring, MD 20910. (301)589–5341
Half restaurant, half food store.
Asem tua/muda. Tamarind. Tua = mature; muda = young or fresh. Also called Asem jawa (“Javanese souring agent”). Mature tamarind—the blocks that are easily available in Indian or SE Asian stores—has to be soaked for several hours or overnight. Sieve out the fibers and seeds. The pulp that remains can be refrigerated for several weeks or frozen. In truth, though, I take a short cut, which is to use the concentrated pulp available in Indian or SE Asian stores, half the amount of tamarind called for in the recipe, with a little water if necessary for texture. The concentrate will keep indefinitely if you refrigerate it after opening. Fresh tamarind is sometimes sold as pods in Indian stores or occasionally SE Asian stores. One Indonesian cookbook recommends boiling these to help separate the pulp from the seeds. (The frozen “tamarind slices” sold in SE Asian stores are not tamarind but another fruit, called gelugur in Indonesian, and not called anything at all in English as far as I can determine.)
Bamboo shoots. Fresh bamboo shoots should be parboiled to remove bitterness—one cookbook recommends using the water that was used for washing rice. They will keep for a long time in the refrigerator; you can slice off pieces as you need them. Canned bamboo shoots do not have to be parboiled.
Bayem. Amaranth, of which there are many kinds. Asian and Indian stores usually have kinds with red in them; Mexican and Caribbean stores have all-green kinds. (The Native Americans in the southwest of the US used an all-red kind as a coloring agent; you won't find this kind at food stores, however.) They should be washed like spinach—dunk them in a bowl of water and then lift them out; repeat many times. Marc Benamou suggests Swiss chard as a very close substitute. Other possibilities, not as close, are other leafy greens such as collards or spinach.
Bean sprouts. Both mung bean and soybean spouts are used in Java; suit yourself.
Ceme. Loofah = sponge gourd; easily available at Chinese stores or at Indian stores that carry fresh vegetables. Substitute any bland, green squash-like thing, such as chayote (“labu siam” in Indonesia), fuzzy gourd, bottle gourd = calabash, or zucchini (which are not used in Java).
Celery. Chinese celery is similar to Javanese celery: it's mostly leaves and very strong in flavor. (It's also excellent in western dishes such as chicken soup.) If you have to use western celery, increase the quantity of leaves somewhat.
Chilis. Two kinds of chilis are commonly used in Java. One is long, maybe 4 to 6 inches, and hot. Both green and red are used. These are fairly common in Chinatown; jalapeños are a reasonable substitute. There are also much smaller chilis that are much hotter (Indonesian cabe rawit) and these are widely available in Asian and Indian markets. The recipe specifies which type is needed.
Coconut milk (santen). Of course, you will make your own from freshly grated coconut; the proportions are given in the recipes. But if the servants have the day off, there is excellent frozen coconut milk from Thailand. This is the kind that lists coconut and water as ingredients. One brand is “Thai Foods.” For mysterious reasons, the supplies are erratic; Thai stores such as Bangkok Center Grocery are the best sources, but sometimes months will go by without any deliveries and nobody seems to know why. It is worth stocking up whenever you can find it. Restaurants generally use canned coconut milk, which is easily available but definitely less good; the best kind is from Thailand. There is also a frozen coconut milk from the Phillipines that lists coconut cream as the prime ingredient; this is no better than canned, more expensive, harder to find, and probably less healthy.
Coriander seeds. Like pepper, these are much better if ground just before use. Unlike pepper, they're not easy to grind. They will split in half easily enough but they resist attempts at further crushing. The whole seeds can be coaxed into submission by roasting them in a dry frying pan for a few minutes until they darken slightly. Roasted coriander seeds can be kept for at least several weeks without noticable loss of flavor. Coriander leaves are not used in Javanese cooking.
Gula Jawa. A dark palm sugar, usually labelled “gula jawa.” There is a light palm sugar from Thailand which is sweeter and less tasty. Gula Jawa is not as sweet as cane sugar, so if you substitute western-style brown sugar, use less, and maybe spike it with molasses (although the flavor is different).
Jackfruit. Young jackfruit is used as a vegetable and, in New York at least, is available only in cans. It is very fibrous and will stand up to long cooking times. Mature jackfruit is sweet and is eaten fresh (you can get it frozen, which is quite good, or canned with syrup, which I've never tried).
Kecap manis. Indonesian sweet soy sauce; available in SE Asian groceries. ABC brand is a big seller in Indonesia.
Kemangi. A type of basil similar to Thai holy basil, but with a green stem, not purple. Sometimes called “lemon basil” in English (although that term seems to include at least two or three different kinds of basil.) There are always several varieties of basil available at Thai groceries such as Bangkok Center Grocery. Any of the oriental varieties can be used, and Western basil is a good substitution; even better is to mix in a few leaves of fresh mint.
Kencur. A rhizome somewhat similar to ginger; greater galingale (sometimes spelled galangale) in English. Available frozen, either as slices or as whole roots, in SE Asian stores. Like ginger, the whole roots can be kept in the freezer and grated as needed. There is a similar rhizome which is a bit easier to find and, if necessary, it can be substituted althogh its flavor is somewhat different; it is lesser galingale or just galingale in English, lengkuas in Indonesian, laos in Malay. Both types are used in Java where they are not considered interchangeable. Incidentally, these were both used in English cooking at least until the 17th century (which is why they have English names).
Kenikir greens. The bitter leaves of a flower (a kind of cosmos). Not available here. You can grow them (google for “kenikir greens”) or substitute chrysanthemum leaves from a Japanese grocery.
Lemper. A large, flat stone bowl used for grinding; sometimes available at Asia Market Corp., or use any stone (not ceramic) mortar.
Lime leaves. Available dried or frozen from SE Asian or Thai stores; the frozen are very much better. This is not our familiar lime, but a different species, the kaffir lime (that term may be derogatory) or makrut, which has bumpy skin, and a more concentrated, less medicinal flavor than the limes we are used to.
Long beans. There are two kinds available all over Chinatown. The darker and skinnier one is more like the Javanese (and is a bit tastier), but either one will do. Substitute western string beans if you have to, although these aren't as flavorful.
Melinjo leaves. These are delicious, unobtainable here, and there is no substitute. It is possible that they can be found lurking in some freezers until their Filipino name bago, their Thai name peesae, their Vienamese name gâm cây, or their botanical name Gnetum gnemon. Marc Benamou believes that extremely young maple leaves might work. One Javanese cook, long resident in the US, uses kale, which is at least a fresh leaf, even though it tastes nothing like melinjo leaves.
Mirih nut. Available in SE Asian stores as kemiri or candlenuts, or substitute macadamia nuts (which taste similar) or even almonds or walnuts (which don't).
Papaya leaves. I haven't found these in stores, but any bitter green will substitute—chicory, perhaps or, better, bitter-melon leaves.
Peanuts. The cheapest source for raw peanuts is Chinese stores. I like to leave the skins on, although not everybody does.
Peté. Also "petai" or, evocatively, "stinkbeans." Available frozen from Thailand as sator or sataw beans. Split these in half before cooking.
Sambal ulek. A hot red-pepper paste widely available (in Chinese stores as well as SE Asian and sometimes Indian stores); sometimes spelled "sambal oelek." It contains red peppers, salt, and lemon juice or vinegar, but not tomatoes.
Tahu. Tofu. The Chinese kind is very widely available and is entirely appropriate.
Tempe. "Indonesian style" tempe is available frozen in SE Asian stores. It is made in this country, but is esentially the same as tempe in Indonesia. The various kinds of refrigerated tempe in supermarkets and health-food stores aren't exactly the same, but will work well, especially the “soy” or “regular” kinds without added vegetables or whatnot.
Terasi. A fermented shrimp paste; easily available in SE Asian stores, perhaps under the Malay name variously spelled “blacan” or “belanchan” or some variation. This must be fried or roasted (in an aluminum-foil packet). A great time saver is pre-roasted terasi from Singapore. This is labelled “Roasted Shrimp Cake (Trassi Bakar).” It will keep indefinitely in a tightly sealed packet in the refrigerator (and, probably, outside of it, too).