Heat the vegetable oil in a large skillet over medium-high heat. Add the ground chuck, half of the onion, 1 teaspoon salt and chile powder; cook, stirring and breaking up the meat with a wooden spoon, until the meat is browned and the onion is tender, about 7 minutes.
2 tbsps. vegetable oil, 1 lb ground beef chuck, 1 large white onion, minced, kosher salt, 1-1/2 tsps. chipotle chile powder
Add the tomatoes, beans and zucchini and cook, stirring occasionally, until the zucchini is just tender, about 6 minutes.
1 (10 oz) can can Fire roasted diced tomatoes with green chiles or Mexican-style diced tomatoes with green chiles, 1 (15 oz) can pinto beans, 1 medium zucchini
Meanwhile, toss the coleslaw mix, lime juice and salt and pepper to taste in a bowl.
2 cups coleslaw mix or finely shredded cabbage, juice of one lime plus lime wedges for serving, freshly ground pepper
Divide the tostadas among plates and spoon the beef mixture on top. Top with the cheese, slaw and the remaining minced onion. Serve with lime wedges.
8 tostadas (flat crisp shell) or taco shells, 1-1/2 cups (about 4 oz) shredded cheddar cheese