Cook the onion in peanut or olive oil, adding salt as soon as you add the onion. Add the spices and the chile. Once the spices are fragrant, add the beans, then add all the liquid and lemon rind. Cook, stirring occasionally, at below a simmer until the beans are very tender, about 1/2 hour. Add the fish sauce if you are using it. Add the vegetables and peanuts and cook for 15 minutes on low heat. When everything seems integrated, taste the curry. Add salt if it needs it and a big squeeze of lemon juice. Serve on rice, topped with fresh herbs.
Excerpted from An Everlasting Meal by Tamar Adler. Copyright © 2011 by Simon & Schuster, Inc. Excerpted with permission by Scribner, a Division of Simon & Schuster, Inc.
Andy Ricker, author of Pok Pok, says each of Thailand's regions has distinct culinary traditions.