Attach sous vide wand to stock pot. Fill pot with water according to manufacturer’s instructions.
Preheat sous vide wand to 160°F.
Place beef and salsa in food-safe plastic bag and seal, removing as much air as possible.
Submerge bag in water. Set timer for 24 hours.
At end of cooking time, carefully remove bag from pot, open bag and pour 1 cup of cooking liquid into small bowl; remove ribs; discard bag. Shred beef with two forks. Remove fat from cooking liquid.
Remove avocado flesh from peel. Use potato masher or fork to lightly smash avocado to spread-like consistency.
Divide ingredients evenly and layer each piece of bread with avocado spread, a tomato slice and shredded beef. Drizzle cooking liquid over each serving. Season with salt and pepper. Serve with wedge of lime.
Nutrition information per serving: 643 Calories; 390.6 kcal Calories from fat; 43.4 g Total Fat; 14.7 g Saturated Fat; 1.8 g Trans Fat; 3.4 g Polyunsaturated Fat; 24.1 g Monounsaturated Fat; 123 mg Cholesterol; 496 mg Sodium; 30 g Total Carbohydrate; 8.2 g Dietary Fiber; 38 g Protein; 0 mg Calcium; 6 mg Iron; 1006 mg Potassium; 0.5 mg Riboflavin; 8 mg NE Niacin; 0.7 mg Vitamin B6; 4.3 mcg Vitamin B12; 320 mg Phosphorus; 13.1 mg Zinc; 43.2 mcg Selenium; 131.8 mg Choline;