Add olive oil to medium saucepan and heat over medium heat. Add onion and garlic and cook for a few minutes. Add spices and heat until fragrant (a few more minutes). Add tomato, black beans and corn. Cook until filling is heated through (about 10 minutes). Top with freshly chopped cilantro and serve.
While taco filling is cooking, prepare taco shells by placing them on a baking sheet. Heat oven to 350 degrees . Heat taco shells in oven for about 5 minutes. Remove from oven and serve with filling and assorted toppings.