Preheat oven to 375℉
I use minute rice and get that going while I cook the ground beef and onions. You can use the rice of your choice. I've also used cooked couscous and it is also delicious in stuffed peppers.
Add the ground beef to a skillet and cook over medium heat, breaking up the meat.
While the ground beef cooks, prepare the peppers by cutting the stem end off. Remove the seeds and any of the core membrane. Use a spoon if needed. Set the hollowed peppers aside until ready for filling.
When the ground beef is no longer pink, add the diced onion and continue to cook an additional 5 minutes to soften the onions.
Add salt, pepper, garlic powder and chili powder to the skillet, stir to combine. While reading the ingredient list it may seem like a lot of salt but keep in mind that you're seasoning the beef mixture and rice.
Combine the cooked rice and ground beef mixture together.
Add about 1/4 c of the tomato sauce to the filling mixture and stir to incorporate everything together.
Use the remaining tomato sauce to cover the bottom of a casserole dish.
Fill the peppers with the beef & rice mixture.
Place each filled pepper into the casserole dish.
Bake the stuffed peppers for 45-55 minutes, or until desired tenderness of the peppers. I prefer around the 45 minute mark. The peppers are tender but still have a slight crunch at that point.
If you are topping with cheese as I have, remove from the oven after 45 minutes and top with the shredded mozzarella. Return the peppers to the oven for an additional 5 minutes until the cheese is melted.
Allow the stuffed peppers to rest 5 minutes after cooking as they will be very hot before serving. Serve on a plate with some of the tomato sauce drizzled next to the pepper.