Combine onion, vinegar, 1/4 cup water, sugar, 1/4 teaspoon salt, and jalapeño slices in a saucepan over high heat; bring to a simmer. Cook 1 minute; remove from heat, and let stand until ready to serve.
While onion mixture cooks, heat a large skillet over medium-high heat. Coat pan with cooking spray. Add ground beef, chili powder, cumin, garlic, paprika, and remaining 1/4 teaspoon salt to pan. Cook 5 minutes or until browned, stirring to crumble. Stir in oil.
Drain onion mixture. Top tostadas evenly with beef mixture, onion mixture, sour cream, and cilantro.
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.
I thought the recipe was really solid. You can put it together in <30 minutes (limited chopping and prep) and it's quite tasty; great for a weeknight. It would also be easy to scale up. Made it according to directions though I subbed ground turkey for the ground beef. The seasoning on the meat isn't anything super special but it's good without being overwhelming. I'd probably use more next time, though results might be different with beef. Jalapeno/pepper mix was outstanding. I'd make that separately just to eat with other dishes, though I'd suggest at least doubling that part of the recipe or at least just the veggies as the recipe as written barely makes enough for 4 tostadas. I wish the recipe included directions for making tostadas. The easy way I used: preaheat oven to 400F, lightly brush medium (too big and it's hard to eat) tortillas lightly with canola oil, bake on one side for 5 minutes til lightly browned, flip, and bake 2-3 minutes til lightly browned. Will be making again soon.
At first I thought, "Who needs a recipe for tostadas?" But the pickled onion makes an incredible difference here. My primary change was to roast a poblano pepper I had in the fridge, dice it, and add it to the meat. I also used rounded heaping measurements of spices and saved some calories by making my own tostadas by brushing thin corn tortillas with just a dab of oil, then putting in a hot oven on a cooky sheet sprayed with cooking spray for just 3 minutes per side. I would agree with other that doubling the onions would be a good idea because they're so delicious.