Preheat oven to 400 degrees F.
In a pot, prepare rice according to the instructions.
Using a large skillet, heat to medium and add olive oil. Add onions and saute until soft, about 4-5 minutes.
Add tomato paste and stir until fragrant, about 1 minute.
Add ground beef and cook, breaking up the meat. Cook until almost no pink remains, approx. 4 minutes.
Drain the fat and return to heat and add garlic.
Continue to cook until no pink remains, approx. 1 more minute.
Add rice and fire-roasted tomatoes. Add the salt, pepper, and oregano.
Reduce heat and simmer until liquid has reduced marginally, about 5 minutes.
Season with additional salt and pepper to taste.
Remove from heat and add 1/2 cup of cheese and mix until combined.
Place peppers cut side up in a 9"x13" baking dish.
Spoon mixture into each pepper.
Take a sheet of aluminum foil and spray with a non-stick spray and cover stuffed peppers.
Bake until peppers are tender, about 30 minutes. Top peppers with remaining cheese and return to oven, uncovered.
Bake until cheese is bubbly, about 10 minutes then remove from oven
Garnish and serve!