In bowl mix together the ground beef, onion, tomatoes, tomato sauce, rice, salt, pepper, garlic and Worcestershire sauce.
Cut tops from peppers; discard seeds and membranes. Sprinkle inside of peppers with salt. Stuff peppers with meat mixture.
Place the 2-piece stainless steel rack on bottom of the CanCooker and add the 12 oz water. Place the stuffed peppers on the rack, latch lid and place on low to low/medium heat. Steam for 40 minutes, then turn off heat.
Sprinkle with cheese, place lid back on and let stand for 10 minutes.