Ingredients
1.5 to 2 pounds flank steak, thinly sliced against the grain
3 large bell peppers (mixed colors), cored and thinly sliced
1 large yellow onion, thinly sliced
1 (1-ounce) packet fajita or taco seasoning mix
1/3 cup lime juice (fresh or bottled)
Directions
Slice the flank steak thinly against the grain into strips about 1/4 inch thick. This helps the meat stay tender after slow cooking.
Place the sliced bell peppers and onion in the bottom of a 4- to 6-quart slow cooker, spreading them into an even layer. These will cook down into soft, caramelized strips that mingle with the steak.
In a medium bowl, whisk together the fajita or taco seasoning mix and the lime juice to create a loose, tangy paste. If it seems very thick, add 1 to 2 tablespoons of water to help it coat the meat.Add the sliced flank steak to the bowl with the seasoning-lime mixture and toss well until every strip is evenly coated.
Spread the seasoned steak strips over the bed of peppers and onions in the slow cooker, arranging them in as even a layer as possible so they cook consistently.Cover and cook on LOW for 5 to 6 hours, or on HIGH for 2.5 to 3 hours, until the steak is very tender and the peppers and onions are soft and lightly caramelized around the edges. Avoid lifting the lid frequently, as that extends cooking time.Once cooked, taste the juices and adjust seasoning if needed by sprinkling in a bit more fajita or taco seasoning or an extra splash of lime juice for brightness. Stir gently to combine the steak with the peppers and onions so everything is well mingled and glossy.
Serve the steak and vegetable mixture with warm tortillas and your favorite simple toppings, or spoon it over rice or salad greens if you prefer a lighter, stove-free dinner.
Variations & Tips
For a bit of heat, use a spicy fajita or taco seasoning packet, or add a pinch of crushed red pepper flakes when you mix the lime juice and seasoning.
If you’d like a smokier profile, choose a seasoning blend that includes chipotle or smoked paprika. To keep the recipe at five ingredients, any toppings (like shredded cheese, sour cream, salsa, or avocado) should be treated as optional add-ons rather than part of the core recipe.
If you prefer chicken, you can substitute boneless, skinless chicken thighs in the same quantity and cook for roughly the same time, checking for doneness at the lower end of the range. For a leaner option, sirloin steak cut into strips can also work, though it can dry out more quickly, so monitor texture.