Method:
Combine vinegar, tamari, ginger and garlic in a medium bowl. Toss sliced beef in mixture and marinate in the refrigerator for 30 minutes.
After beef has marinated, heat a large skillet over medium-high heat. Add beef and marinade and cook until beef is just done to your liking, about 5 minutes. Remove beef and juices to a bowl, cover and keep warm. Add ½ cup water to the skillet, bring to a simmer, add shallots and cook 3 minutes or until tender. Stir in bell peppers and carrots. Reduce heat to medium and cover. Cook until vegetables are just fork tender, 7 to 8 minutes, stirring once. Uncover and increase heat to medium-high. Add snow peas and cook 2 minutes longer. Return beef and any juices to skillet and cook 1 minute longer to heat everything thoroughly. Serve with cooked brown rice and garnish with cashews.