Set aside green onions and 1/2 the basil for garnish.
In a large (6 quart) stockpot over low heat, sauté onions in oil until soft and clear, about 30 minutes, stirring once or twice. (You can do it faster, but the flavor is never the same.) Add garlic, chopped pepper, carrots and celery and sauté for 15 minutes , stirring occasionally.
Add all the remaining ingredients to the pan with enough water to almost cover the vegetables. Stir well and raise the heat to bring to a boil. Lower heat to low, cover and cook for one hour, stirring once or twice during that time.
After an hour, take a look and test the squash with a fork. If the fork pierces it easily it is ready. Taste the broth. Too thin? Mash some of the veggies to thicken the broth. Too thick? Add some water and cook a little while longer. Need salt? Add a little soy sauce or tamari. Need spice? Add some cayenne, Tabasco or black pepper. Too salty? Add a little sugar. Too flat? Add a little rice wine vinegar or lemon.
Serve over couscous or rice. Garnish with reserved basil and scallions. Serves 4-6.
* Curry Paste can be found in most Asian markets