In a medium saucepan, bring 2 cups of water to a boil. Add the rice, reduce heat to low, cover, and simmer for 15 minutes or until the rice is tender and water is absorbed. Remove from heat and fluff with a fork.
While the rice cooks, heat olive oil in a large skillet over medium-high heat.
Add the chopped onion and cook for 3-4 minutes until softened.
Add the minced garlic and cook for 30 seconds until fragrant.
Add the ground beef to the skillet, breaking it up with a spoon. Cook until browned and cooked through, about 6-8 minutes.
Stir in chili powder, ground cumin, smoked paprika, dried oregano, salt, and black pepper. Cook for another 2 minutes to let the spices blend.
Add the black beans and corn to the skillet, stirring to combine and heat through for 2-3 minutes. Remove from heat.
To assemble each taco bowl, divide the cooked rice evenly among four bowls.
Top each bowl with the seasoned ground beef mixture.
Sprinkle shredded cheddar cheese over the warm beef and rice.
Add diced tomato, chopped cilantro, and diced avocado on top.
Add a dollop of sour cream to each bowl.
Serve with lime wedges on the side for squeezing over the bowls.