Set oven to 420F/216C.
Mix together the ingredients for the marinade.
Slice flank steak in half horizontally in order to make it thinner. Then cut each half into 3 equally sized strips. Place the strips in the marinade and marinate for 30 minutes or overnight in the fridge.
Place 2 asparagus spears, 2 slices bell pepper and a few long slices of onion on the thickest end of the strip. Roll it closed. Repeat. TIP: you can use a toothpick in order to close it, OR you can simply place it flap-side down in a skillet or baking sheet.
OPTION A: Spray a nonstick skillet on medium heat and spray with a little olive oil. Once the skillet is hot, add the rolls with the flap-side facing down so that as it sears, it seals the roll. Use tongs to gently pick up and sear other parts of the roll. Sear for about 3 to 5 minutes, being careful not to damage the rolls. Place the entire skillet in the oven for 12 – 15 minutes.
OPTION B: Alternatively, simply place the rolls with a flap-side down onto a baking sheet lined with parchment paper. Lightly spray them with olive oil and bake for 15 to 20 minutes, or until the outside edges have browned significantly and the steak is cooked to your desired readiness.
Enjoy the rolls meal with steamed cauliflower pearls for a lighter, low-carb solution. To make it heartier, add some black beans or avocado if you’re looking to increase the fat content for keto.