Preheat oven to 350 degrees. Wash and clean peppers. Cut off tops and remove seeds and membrane. Place prepared peppers on steamer rack in wok or Dutch oven and steam 3 to 4 minutes.
Meanwhile, heat oil in wok or large skillet, add onion and garlic. Saute 1 minute. Add herbs, carrots and peas. Continue to cook 3 to 5 minutes or until carrots are tender, stirring constantly. Reduce heat and add the tomato, walnuts, brown rice and 1/2 cup tomato sauce. Heat through.
Stuff mixture into peppers. Spread 1/2 cup sauce in bottom of baking dish. Stand peppers upright. Pour remaining sauce over the tops of peppers. Bake in oven for 30 minutes.
