2 Tbsp oil
1 lb yellow onions, peeled and thinly sliced
1 tsp sugar
1/4 tsp dried thyme
1/4 tsp black pepper
6 cups vegetable or chicken broth, preferably low sodium
Heat the oil in a soup pot or Dutch oven over moderate (not high!) heat. (High heat may make the onions slightly bitter, but long, slow cooking brings out their sweetness.) Add the onions and sugar and sauté, stirring frequently, until the onions are a rich caramel color, about half an hour. Stir in the thyme and pepper and sauté one minute more. Add the broth and let the soup simmer at least 15 minutes.