Beefy Sweet Potato Mash-Up

Ingredients

• 1 pound Ground Beef (96% lean)
• 1/2 cup water, divided
• 4 teaspoons taco seasoning mix, divided
• 1 large sweet potato, cut into 1/2-inch cubes (about 2-1/2 cups)
• 1-1/2 cups diced yellow onions
• 1 tablespoon vegetable oil
• 1/4 cup plain nonfat Greek-style yogurt
• 1/2 teaspoon hot pepper sauce
• 2 tablespoons chopped fresh cilantro leaves
• 8 small corn tortillas ( 6 to 7 inch-diameter), warmed (optional)