Making your own Thai chili pastes, or curry pastes, can be quite a challenge but it is really worth the effort. You will like being able to control all the ingredients and make the paste come out tasting just right. Many commercially available green curry pastes are way too salty to get all the rich flavors without over salting your dish, and nothing beats the texture and rich green color of a homemade strong green chili paste (พริกแกงขียว) for your next Kaeng Kiew Waan Gai.
Obtaining all of the correct ingredients to make homemade Thai curry pastes is nearly impossible in some areas. Fresh Kaffir lime is not widely available, but in most cities you'll find dried Kaffir lime leaves packaged the way you'll see Bay leaves. These have similar flavors and do make an okay substitute for the rind of the fruit. Some recipes skip the fruit altogether, knowing that most cooks will never be able to get it. We recommend that you try for everything, then just leave out the things you can't get. Thai curry has such an array of different aromas and flavors that you may not even taste that something is missing.