Rinse spears under cold water and pat dry. Snap or trim woody ends — bend near the base and it breaks naturally, or cut about an inch off the bottom. Peel the lower stalks of thicker spears with a vegetable peeler for even cooking. Season lightly with salt, a drizzle of olive oil, and optional aromatics like lemon zest or fresh herbs. Lay spears flat and parallel in a single layer in a zip-lock or vacuum-seal bag. Remove all air — use a vacuum sealer or the water displacement method by slowly lowering a zip-lock bag into the water bath before sealing.

Set your sous vide cooker to 180°F and let the bath fully preheat. Submerge the sealed bag, clipping it to the side so spears stay fully submerged with water circulating freely. Cook thin spears 6–10 min, medium spears 10–15 min, thick spears 20–30 min. Check doneness by pressing through the bag — spears should yield to light pressure but not feel mushy. When in doubt, open the bag and pierce the thickest spear with a paring knife; it should be tender throughout with slight resistance at the center.

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.