Cook cumin seeds in a large saucepan over medium heat 1 minute or until toasted. Remove seeds from pan.
Heat oil in saucepan over medium heat until hot. Add 1 teaspoon toasted cumin seeds, chopped onion, and sugar; sauté 5 minutes or until onion is lightly browned. Stir in flour, chili powder, and garlic. Add squash, water, hominy, and broth; bring to a boil. Cover, reduce heat, and simmer 10 minutes. Uncover and simmer an additional 10 minutes or until squash is very tender and stew thickens. Stir in 1 teaspoon toasted cumin seeds, chopped bell pepper, and cilantro.