Bistec a la Criolla Recipe (Colombian -Style Creole Steak)

Ingredients

For 4 servings

• 2 pounds sirloin or skirt steak (trimmed and cut into 4 equal portions)
• 3 garlic cloves (minced)
• 1/2 tablespoon yellow mustard
• 1 tablespoon ground cumin
• Salt and black pepper (to your taste)
• 2 tablespoons fresh cilantro or parsley (chopped)
• 2 tablespoons vegetable oil
• 1 cup onion (sliced)
• 2 tomatoes (diced)