In a large skillet, sauté onions and jalapeño over medium low heat until onions start to soften and turn translucent, 2-3 minutes. Stir in garlic and cook 1 minute more. Increase heat and add ground beef to skillet and brown until cooked through. Add beef broth, tomato sauce, chili powder, sugar, cumin, salt and pepper to pan and stir to combine. Let simmer over low heat for 10 minutes or until sauce has reduced slightly. 

Meanwhile in a second smaller skillet, lightly fry corn tortillas in hot vegetable oil. Tortillas should still be pliable for rolling. Set tortillas aside with paper towels between each layer. Once sauce has reduced slightly, stir in 2 tablespoons of chopped fresh cilantro.

Preheat oven to 400 degrees and spray a 9x13 baking dish with non stick cooking spray.

To assemble enchiladas, start by adding 1/2 cup of enchilada sauce mixture in bottom of baking pan. Use a slotted spoon to evenly divide meat mixture into each of the tortillas, then divide 8 oz of cheese between all 12 enchiladas, roll and place seam side down in baking dish. Pour remaining enchilada sauce over rolled enchiladas and top with remaining cheese.

Cover dish with foil and bake at 400 degrees for 20-30 minutes, or until heated through and hot and bubbly. Sprinkle with additional fresh cilantro and serve with sour cream.