Heat oil in a skillet over MEDIUM-HIGH heat. Add Ground Beef and diced onions, breaking up with a spoon. Cook for 8-10 minutes, breaking beef into small crumbles and stirring occasionally. Drain any excess grease from the pan, then return to the stove and reduce heat to LOW.
Add garlic powder, chili powder, cumin, salt, pepper, and lime juice. Stir to combine and allow to simmer for 5 minutes.
To assemble tostadas, spread warm refried beans on tostada shells, top with ground beef and serve with salsa, queso fresco and lime wedges.
Nutrition information per serving: 450 Calories; 211.3 Calories from fat; 23.6 g Total Fat (7.8 g Saturated Fat; 8.5 g Monounsaturated Fat); 71.2 mg Cholesterol; 1316.7 mg Sodium; 32.3 g Total Carbohydrate; 0.8 g Dietary Fiber; 28.3 g Protein; 4.4 mg Iron; 748.5 mg Potassium; 0.3 mg Riboflavin; 7.5 mg Niacin; 0.5 mg Vitamin B6; 2.2 mcg Vitamin B12; 6.1 mg Zinc; 23.7 mcg Selenium; 112.6 mg Choline.
This recipe is an excellent source of Protein, Iron, Riboflavin, Niacin, Vitamin B6, Vitamin B12, Zinc, Selenium, Choline. It is a good source of Potassium.