Cheesy Beef Crunch Tacos

Name: Cheesy Beef Crunch Tacos
Ingredients: 1 medium red onion, finely chopped, divided; 1 small jalapeño, sliced; 1 tbsp. fresh lime juice; Kosher salt and pepper; 2 tsp. olive oil; 2 cloves garlic, grated; 1 lb. ground beef (85% lean); 2 tsp. ground cumin; 1 tsp. smoked paprika; 1 tsp. chili powder; 1/2 tsp. dried oregano; 1 10-ounce can petite diced tomatoes with jalapeño and cilantro; 8 6-inch flour tortillas; 8 hard taco shells; 4 oz. pepper Jack cheese, coarsely grated (11/2 cups); 1 tomato, chopped; 1/3 c. cilantro leaves