In a medium saucepan over medium heat melt butter together with olive oil. Add rice and stir to coat. Cook, stirring frequently until rice is toasted.
Stir in chicken broth, tomato sauce, chili poweder, garlic salt, cumin, oregano, and diced tomatoes with green chilies. Stir well, reduce heat to low, place the lid on the pot and cook on low for 20 minutes.
After 20 minutes, remove lid, fluff rice, and add corn and black beans. Replace the lid and let sit for 5 minutes or so on very low heat.