How to make it
Place sirloin steak onto a bowl or plate with the Lee Kum Kee Panda Brand Cooking Soy Sauce. Coat well, cover and let marinate for two hours before cooking. Preheat oven to 400°F.
Cut about 1" down from the top of the green peppers, then removed the seeds and whites. Place on a sheet pan and drizzle with 2 Tbsp. olive oil and season with salt and pepper. Bake them for 10 minutes. Once cooked, take out and set aside.
In a pan, heat up the remaining olive oil and then sear the steak for 1 minute per side then remove from heat and let cool.
In the same pan, add in the mushrooms and sliced onions. Cook them down for 3 minutes and then add in the sliced red pepper and cook for another 2 minutes until all have softened. Season them with salt and pepper. Cut steak into thin slices, across the grain once cooled and combine with sautéed veggies.
Then fill the green peppers with cooked veggies and the steak. Fill all 4 of them up, then top with shredded mozzarella cheese and place back into the oven to bake for 5-10 minutes until the cheese is melted. Plate and serve right away.