May Fiesta: Just 5 ingredients. I make it when craving something zesty but absolutely refuse to stand over a hot stove all evening.

These 5-ingredient slow cooker steak fajitas are my answer to those May evenings when I want something bright and zesty but have no interest in hovering over a hot stove. Fajitas, originally from Northern Mexico and popularized in Tex-Mex cooking, traditionally use quick-seared strips of marinated skirt or flank steak with peppers and onions.

Here, we borrow that flavor profile but let the slow cooker handle the work, so you end up with succulent, glistening strips of steak tangled with soft, caramelized peppers and onions—perfect for piling into warm tortillas with minimal effort.

Serve these slow cooker steak fajitas on warm flour or corn tortillas with a squeeze of fresh lime and whatever simple toppings you like: a spoonful of salsa, sliced avocado, or a dollop of sour cream all work beautifully. A side of black beans or Mexican-style rice makes this a complete meal, and a crisp green salad with a citrusy vinaigrette balances the richness of the beef.

If you’re entertaining, set everything out family-style so people can build their own fajitas and add their preferred garnishes.

5-Ingredient Slow Cooker Steak Fajitas

Servings: 4

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.

To avoid mushy vegetables, slice the bell peppers into thicker strips (about 1/2 inch) so they hold some shape after several hours in the slow cooker.

Food safety tips: always slice the raw flank steak on a clean cutting board, then wash the board, knife, and your hands thoroughly with hot, soapy water before handling other ingredients. Keep the slow cooker covered while cooking to maintain a safe temperature, and ensure the beef reaches at least 145°F internally; in practice, it will be well above that by the time it is tender.

Refrigerate leftovers within 2 hours of cooking in shallow containers, and reheat to at least 165°F before serving again. Leftovers make excellent next-day fajita bowls over rice or tucked into quesadillas.