Heat olive oil in a large skillet over medium-high heat.
Add diced onion and cook for 3-4 minutes until softened.
Add minced garlic and cook for 30 seconds until fragrant.
Add ground beef to the skillet and cook, breaking it apart with a spoon, until browned and cooked through, about 6-8 minutes.
Stir in chili powder, ground cumin, smoked paprika, dried oregano, cayenne pepper, salt, and black pepper. Cook for 1-2 minutes to toast the spices and combine flavors. Remove from heat.
While the beef cooks, rinse the rice under cold water until water runs clear.
In a medium saucepan, bring 2 cups of water to a boil.
Add the rinsed rice to the boiling water, reduce heat to low, cover, and simmer for 15 minutes or until rice is tender and water is absorbed.
Remove rice from heat and let it sit covered for 5 minutes, then fluff with a fork.
To assemble the taco bowls, divide the cooked rice evenly among four bowls.
Top each bowl of rice with seasoned ground beef, black beans, thawed corn, and halved cherry tomatoes.
Sprinkle shredded cheddar cheese over the top while the beef is still warm so it melts slightly.
Add diced avocado and chopped fresh cilantro to each bowl.
Serve each bowl with a lime wedge and a dollop of sour cream on the side.