Here is a foolproof, budget-friendly way to get incredibly tender, flavorful steak with almost zero effort. By cooking the steak in sealed foil packets inside your slow cooker, you essentially “braise” the meat, allowing it to soak up the Cajun spices and butter without drying out.
This recipe is perfect for busy weeknights, and because it only uses 3 core ingredients (plus optional toppings), it is a lifesaver when you don’t have time to stand over a grill or stove.
Why this works
Slow cookers are a moist-heat environment. Sealing the steak in a foil packet traps the butter and the steak’s natural juices directly against the meat, poaching it gently. The Cajun seasoning acts as a dry brine, penetrating the steak while it cooks.
Ingredients
The “Big 3”:
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2 lbs Sirloin Steak, Flank Steak, or Chuck Steak (Look for a cut that is about 1 to 1.5 inches thick)
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2 – 3 tbsp Cajun Seasoning (Use a store-bought blend like Slap Ya Mama or Tony Chachere’s, or see the homemade blend below)
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1 stick (1/2 cup) Salted Butter
Optional but Recommended Add-ins:
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1 large Yellow Onion, sliced into rings
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1 Green Bell Pepper, sliced
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Fresh parsley for garnish
Instructions
1. Prep the Slow Cooker and Foil
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Tear off 4 large sheets of heavy-duty aluminum foil (about 12×12 inches each). You want them big enough to wrap a piece of steak loosely, but tightly sealed.
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Pro Tip: If you only have regular foil, double it up to prevent the steak bones or seasoning from tearing the packet.
2. Season the Steak
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Pat the steak completely dry with a paper towel. (Dry meat grabs the seasoning better).
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Cut the steak into 4 equal portions.
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Generously coat every side of each piece of steak with the Cajun seasoning. Don’t be shy—you want a nice crust of flavor, but be mindful if you are using a store-bought blend that is high in salt.
3. Build the Packets
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Place a few slices of onion and pepper (if using) in the center of the foil. This creates a “rack” for the steak to sit on, preventing the bottom from scorching.
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Place a piece of seasoned steak directly on top of the veggies.
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Cut the butter into 8 pats. Place two pats of butter directly on top of each steak.
4. Seal the Packets
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Bring the left and right sides of the foil up and fold them together at the top. Roll the fold down tightly to the steak.
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Fold the open left and right ends inward tightly to create an airtight seal. You want the steam and butter to stay inside.
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Place the sealed packets into the basin of your slow cooker. You can stack them, but try to leave a little space for air circulation if possible.
5. Cook Low and Slow
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For Sirloin/Flank Steak (Medium to Medium-Well): Cook on LOW for 4–5 hours.
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For Chuck Steak/Roast (Fall-apart tender): Cook on LOW for 6–7 hours.
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Avoid cooking on HIGH. High heat will cause the meat to seize up and become tough.
6. Rest and Serve
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Carefully remove the packets from the slow cooker using tongs (they will be full of hot liquid and steam). Place them on a plate or baking sheet.
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Open the packets very carefully—the steam will be scalding.
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Let the steak rest in the open packet for 5 minutes so the juices redistribute.
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Spoon the melted butter, Cajun spices, and onions from the bottom of the foil over the steak. Serve as-is, or slice thinly against the grain.
Homemade Cajun Seasoning Blend
If you don’t have a pre-made blend, mix this together. This makes about 3 tablespoons:
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1 tbsp smoked paprika
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2 tsp garlic powder
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1 tsp onion powder
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1 tsp dried oregano
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1 tsp dried thyme
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1/2 tsp cayenne pepper (adjust to your spice preference)
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1 tsp black pepper
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1 tsp salt
How to Serve
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Low Carb: Serve the sliced steak and onions over cauliflower rice.
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Classic Comfort: Serve over a bed of buttered white rice or mashed potatoes to soak up all the buttery Cajun juices.
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Sandwich Style: Slice the steak thin, pile it onto a hoagie roll with the peppers and onions, and top with provolone cheese.