Gather all of the ingredients together beforehand. Preheat the oven to 400° F.

Using a small pot, cook the rice according to the package instructions.

Then, using a separate skillet heat the oil over medium heat. You will want to use a large skillet because you will be adding a lot of ingredients to this before you stuff your peppers.

Next, add the onion and cook it until it is soft, about 4 minutes. To that, add in the tomato paste and garlic, and stir to combine. Cook this until it is fragrant, about 1 minute.

To this mixture, add ground beef, and work to break up the meat with a wooden spoon. Allow the cooked beef to brown a bit to develop flavors and color. Carefully drain the fat.

Return the pan to the stove. Next, stir in the cooked rice and diced tomatoes. Season this mixture with oregano, salt, and pepper. Let this mixture of beef, tomato, and rice simmer until the liquid has reduced slightly.

Next, carefully place the bell peppers cut side up in a 9"-x-13" baking dish. Spoon the beef mixture into each pepper and top them with the Monterey jack cheese.

Cover the baking dish with foil. Put the dish in your preheated oven, and bake this until the peppers are fork-tender, about 35 minutes.

Uncover and bake until the cheese is bubbly, 10 minutes more.

Garnish with parsley before serving.