1. Heat a large saucepan over medium heat. Add oil; swirl to coat. Add chopped onion and garlic; sauté 4 minutes. Add beef to pan; cook 5 minutes or until browned, stirring to crumble. Stir in oregano, cumin, and cinnamon; cook 1 minute. Add 1/2 cup water and the next 4 ingredients (through tomatoes). Cover, reduce heat to low, and simmer 20 minutes, stirring occasionally. Stir in cilantro, vinegar, and jalapeño.
2. Heat a grill pan over medium-high heat. Coat with cooking spray. Add onion slices to pan; grill 4 minutes on each side. Remove onion from pan. Place buns, cut sides down, on grill pan; grill 1 minute or until toasted.
3. Place 1 lettuce leaf on bottom half of each bun; top each with 1/2 cup beef mixture. Divide onion slices evenly among servings; top with top halves of buns.
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.