In a dutch oven or flameproof skillet, heat the oil over medium-high heat. Add the zucchini and red pepper. Cook, stirring occasionally, until lightly browned, about 5 minutes. Add the scallions, chile pepper, and garlic. Cover and cook, stirring often, until the vegetables soften, about 2 minutes.
Stir in the corn. Cook, uncovered, until the corn is heated through, stirring occasionally, about 2 minutes.
Add the broth, bring to a boil, and cook until slightly reduced, about 2 minutes. Add the sour cream, tomatoes, cumin, and oregano. Stir gently just until heated through, about 1 minute. Do not let the sour cream come to a boil or it may curdle. Season with salt and pepper.
Spoon the cooked rice into individual soup bowls and top with the fricassee. Garnish with the cilantro or oregano sprigs and serve immediately.