In a large sauce pan, heat oil over medium heat. Add chili powder and flour whisking constantly to combine. Mixture will be a thick paste-like (roux) and will be deep red in color. Add in about 1/4 cup of the tomato sauce whisking until the roux has dissolved (very important to whisk while adding tomato sauce - whisk until smooth). Once the roux is smooth, add remaining tomato sauce and beef broth. Whisk to combine. Add in onion powder, garlic powder and cumin and stir to combine. Bring to a boil, reduce heat and simmer for 15 minutes or until slightly thickened - stirring occasionally. While enchilada sauce is simmering, cook steak in frying pan by drizzling pan with olive oil and cooking steak. Try to get a slight char on the steak. Once steak is cooked, ladle 3 spoonfuls of enchilada sauce over steak and cook over medium heat for 5 minutes. Remove from heat. Prepare corn tortillas by lightly warming in a skillet until warm. Finely chop white onion and cilantro and use to garnish tacos (to taste) as shown in the picture. Authentic mexican tacos are spritzed with lime and finished with a small pinch of salt before serving. Add avocado for garnish is using.