Whether being used to fill a taco, top a panucho, or stuff a gordita, savory fillings or toppings complete many a Mexican dish. Although the combinations are endlessly variable, these four are among our favorites.

INGREDIENTS

• 1 tablespoon vegetable oil
• 1 small onion, chopped fine
• 1 serrano chile, stemmed, seeded, and minced
• 2 tablespoons tomato paste
• 3 garlic cloves, minced
• 1/2 teaspoon dried oregano
• 1 cup vegetable broth
• Salt and pepper
• 1 pound zucchini, cut into 1/2-inch pieces
• 1 tablespoon chopped fresh cilantro
• 2 scallions, sliced thin
• 4 ounces Cotija cheese, crumbled (1 cup)

INSTRUCTIONS

1. Heat oil in 12-inch nonstick skillet over medium heat until shimmering. Add onion and serrano and cook until lightly browned, about 8 minutes.
2. Stir in tomato paste, garlic, and oregano and cook until fragrant, about 1 minute.
3. Stir in broth, 1 teaspoon salt, and 1/2 teaspoon pepper and simmer until slightly thickened, about 6 minutes.
4. Stir in zucchini, cover, and cook until zucchini is slightly softened, 5 to 7 minutes.
5. Uncover, increase heat to medium-high, and cook, stirring often, until sauce has thickened and coats zucchini, about 4 minutes.
6. Off heat, stir in cilantro and season with salt and pepper to taste.
7. Garnish with scallions and Cotija.