在冷水下冲洗矛，拍干。摘下或修剪木质末端——在基座附近弯曲并自然断裂，或从底部切割约一英寸。用蔬菜削皮器去皮较厚矛的下茎以获得均匀烹饪。用盐、橄榄油的小流和柠檬皮条或新鲜草本植物等可选香料轻轻调味。在拉链锁或真空密封袋中将矛放平和平行的单个层中。去除所有空气——使用真空封口机或水排移方法，通过慢慢将拉链锁袋降低到水浴中，然后在密封前密封。

将真空低温烹饪器设置为180°F并让水浴完全预热。将密封食品袋浸没，将其夹在一侧，使矛笋完全浸没且水能自由循环。烹饪薄矛笋6–10分钟，中等矛笋10–15分钟，粗矛笋20–30分钟。通过按压食品袋外部检查熟度——矛笋应该在轻压下有所松动，但不应感到软烂。如有疑问，打开食品袋并用削皮刀刺穿最厚的矛笋；它应该从头到尾都很嫩，中心有轻微阻力。

Remove the bag from the water bath and open carefully. Transfer spears to a plate. Serve immediately as-is, or sear in a very hot pan for 30–60 seconds per side for color and caramelization. Finish with flaky salt and a squeeze of fresh lemon juice. Asparagus does not hold well — eat right away. Avoid: Don't add the bag before the water bath is fully preheated. Don't overcrowd the bag. Don't leave thin spears past the 10-minute mark or they'll go soft.