In a large saucepan, saute stew meat and onions in oil. Add the diced tomatoes, HERDEZ® Salsa Casera, HERDEZ® Salsa Verde, chicken broth, salt, pepper, garlic powder and ground cumin. Cover and simmer over low heat until the meat is tender, about 1 1/2 hours. During the last 30 minutes of cooking, add the diced potatoes. To serve, spoon stew into warm bowls and serve with warm flour tortillas on the side.