Step 1

Attach sous vide wand to stock pot. Fill pot with water according to manufacturer's instructions.

Step 2

Preheat sous vide wand to 141°F.

Step 3

Combine marinade ingredients in small bowl. Place steak and marinade in food-safe plastic bag; turn to coat. Seal bag, removing as much air as possible, and marinate in refrigerator for 1 hour.

Step 4

Meanwhile, add peppers, onions, garlic, olive oil, salt and pepper to a food-safe plastic bag; toss to coat. Seal bag, removing as much air as possible.

Step 5

Remove steak from refrigerator and submerge both bags in water. Set timer for 90 minutes.

Step 6

At end of cooking time, carefully remove bags from pot.

Step 7

Preheat grill pan or grill, and cook steak 2 to 3 minutes on each side or until internal temperature reaches 145°F. Carve steak diagonally across the grain into thin slices. Place steak slices on tortillas; top with vegetables. Season with salt and pepper, as desired. Serve with guacamole, if desired.