1. Stir together lime juice, water, and next 4 ingredients (through pepper) in a cup; set aside.
2. Heat a large, heavy skillet (such as cast iron) over high heat; lightly coat with cooking spray. Working in batches, if necessary, add steak to hot skillet in single layer; cook, without turning, until browned on 1 side and almost fully cooked (1-2 minutes). Transfer to a plate.
3. Heat oil in skillet over high heat. Add snap peas and cook until bright green and beginning to blister (2-3 minutes). Add jalapeño, peanuts, reserved beef (with juices), and reserved sauce to pan; cook until beef is done (about 1 minute). Toss with mint. Serve over brown rice, if desired.
MyRecipes is working with Let's Move!, the Partnership for a Healthier America, and USDA's MyPlate to give anyone looking for healthier options access to a trove of recipes that will help them create healthy, tasty plates. For more information about creating a healthy plate, visit www.choosemyplate.gov.