In a pan over medium heat add oil and sauté bell peppers for 1 minute. Remove and set aside. Add onions, garlic and cook until translucent. Add pork and cook until lightly browned for about 4 to 5 minutes. Add fish sauce and cook for another 1 to 2 minutes. Add soy sauce, tomato sauce, water and bay leaf then bring to a boil. Reduce heat to simmer, cover and continue to cook for about 20 to 30 minutes or until pork is fork tender and sauce is reduced. Add sweet peas and cook for 2 to 3 minutes. Add bell peppers and cook for another 1 to 2 minutes. Season with salt/pepper to taste. Serve hot over rice.