2 Tbsp vegetable oil
1 lb ground beef chuck
1 large white onion, minced
salt
1-1 1/2 tsp chipotle chile powder
1 10-oz can Mexican-style diced tomatoes with green chiles
1 15-oz can pinto beans, drained
1 medium zucchini or yellow squash, diced
2 cups coleslaw mix or shredded cabbage
juice of 1 lime, plus lime wedges for serving
pepper
8 tostadas (flat crisps tortillas) or taco shells
1 1/2 cups shredded cheddar cheese (about 4 oz)