Mexican Beef Tostada Salad

Ingredients

• 2 tsp wine vinegar
• 1 tsp lime juice
• 1 large tomato (diced)
• 3/4 lb lean ground beef
• 2 tsp chili powder
• 1 cup tomato juice ((use low-sodium if you're watching your salt intake))
• 1/4 cup plain low-fat yogurt
• 4 soft whole-wheat tortillas (each 6-in. diameter)
• Small handful fresh cilantro (chopped)
• 5 cups romaine lettuce (shredded)
• 1 clove garlic (minced)
• 2 green onions