Attach sous vide wand to stock pot. Fill with water according to manufacturer’s instructions.
Preheat sous vide wand to 141°F.
Season steaks with salt and pepper, place in food-safe plastic bag with garlic, rosemary, thyme and seal, removing as much air as possible. Set aside.
Place asparagus, onions, butter, salt and pepper in separate food-safe plastic bag and seal, removing as much air as possible.
Submerge vegetable bag in water and set timer for 45 minutes. When timer goes off, submerge bag with steaks in same stock pot and cook for an additional hour.
At end of cook time, carefully remove bags from water.
Preheat cast iron or large skillet over medium heat. Remove steak from the bag; discard bag, including rosemary and garlic. Cook steak 2 to 3 minutes on each side or until internal temperature reaches 145°F.
Nutrition information per serving: 326 Calories; 95.4 kcal Calories from fat; 10.6 g Total Fat; 4.9 g Saturated Fat; 0.5 g Trans Fat; 0.7 g Polyunsaturated Fat; 4.2 g Monounsaturated Fat; 93 mg Cholesterol; 57 mg Sodium; 26.6 g Total Carbohydrate; 5.1 g Dietary Fiber; 33.4 g Protein; 0 mg Calcium; 5.8 mg Iron; 917 mg Potassium; 0.6 mg Riboflavin; 6.8 mg Niacin; 0.8 mg Vitamin B6; 4.2 mcg Vitamin B12; 324 mg Phosphorus; 4.9 mg Zinc; 28.5 mcg Selenium; 86.7 mg Choline;