Sauté onion and garlic in hot oil in a large Dutch oven until tender. Add poblano pepper and bell pepper, and sauté 2 to 3 minutes. Stir in chili powder, cumin, and oregano; cook, stirring constantly, 1 to 2 minutes.
Add 3/4 teaspoon salt, tomatoes, and next 4 ingredients; bring mixture to a boil. Reduce heat, and simmer 15 to 20 minutes or until zucchini is tender.
Combine flour, cornmeal, baking powder, and remaining 1/2 teaspoon salt in a medium bowl. Cut in shortening with a pastry blender until mixture is crumbly. Stir in cheese and cilantro. Add milk, stirring just until ingredients are moistened.
Drop dough by heaping tablespoonfuls into simmering ragoût. Cook 5 minutes. Cover and cook 10 to 15 more minutes or until dumplings are done.