Preheat the oven to 400 degrees F (205 degrees C). Grease a 9 x 13-inch baking dish then set aside.
Slice each zucchini in half lengthwise. Using a melon baller, hollow out the center of each zucchini. Lightly brush the tops with one teaspoon of olive oil then place them skin-side-down in the casserole dish.
Warm the tablespoon of olive oil in a large skillet over medium heat. Add the onions and peppers and cook for 2 to 3 minutes.
Add the rice, corn, beans, salsa, chili powder, and cumin. Stir everything together and continue to cook for about 5 minutes. Remove the skillet from the heat and set it aside.
Stir in 1/4 cup of the cilantro and salt to the filling. Spoon the filling inside each zucchini until they are full. Sprinkle each one with cheese, then arrange them in the dish and cover with foil.
Bake in the oven for 25 minutes then remove the foil and set the oven to broil. Cook for 5 more minutes until the cheese is bubbly and golden brown.