Add watermelon and 2 tablespoons lime juice to food-safe plastic bag and seal, removing as much air as possible. Refrigerate for 2 hours.
Meanwhile attach sous vide wand to stock pot. Fill pot with water according to manufacturer instructions.
Preheat sous vide wand to 141°F.
Add beef, lime juice, salt and cilantro to food-safe plastic bag and seal, removing as much air as possible.
Submerge bag in water for 45 to 60 minutes. Carefully remove from bag; discard bag.
Preheat non-stick skillet or grill to medium. Cook steak 2 minutes on each side to 145°F for medium-rare doneness. Rest 5 minutes. Slice into 3/4-inch cubes. Season with salt and pepper as desired.
Remove watermelon from bag; discard bag. Slice watermelon into cubes. Divide greens, watermelon, farro and beef evenly among 4 plates. Top with balsamic vinaigrette, as desired.
Nutrition information per serving: 419 Calories; 119.7 kcal Calories from fat; 13.3 g Total Fat; 2.6 g Saturated Fat; 0.2 g Trans Fat; 0.3 g Polyunsaturated Fat; 1.7 g Monounsaturated Fat; 56 mg Cholesterol; 635 mg Sodium; 47.6 g Total Carbohydrate; 4.4 g Dietary Fiber; 29.7 g Protein; 0 mg Calcium; 3 mg Iron; 667 mg Potassium; 0.2 mg Riboflavin; 6.9 mg Niacin; 0.6 mg Vitamin B6; 1.2 mcg Vitamin B12; 218 mg Phosphorus; 4.3 mg Zinc; 26.3 mcg Selenium; 94.1 mg Choline;