Rinse the asparagus under running water, especially around the flowery tips, then pat dry.
To trim the woody ends, you can either bend one spear near the base and let it naturally snap, or cut off the bottom 1 to 2 inches where the color changes from pale white-green to a deeper green.
Prep the garlic and miso
Finely mince the garlic. In a small bowl, combine the miso paste with the stock and stir well until the miso dissolves.
Sauté
Preheat a large 12-inch sauté pan over medium heat until it feels warm but not smoking hot.
Add the butter and oil and swirl to coat the pan. As soon as the butter melts, add the garlic and sauté for 10 seconds.
Add the asparagus
Add the asparagus to the pan. Sauté by gently shaking the pan back and forth and using tongs or a wooden spatula to flip the spears so they cook evenly, about 2 minutes. You should hear a gentle sizzle the whole time.
Add the miso mixture
Give the miso mixture another stir, then pour it into the pan.
Keep tossing and sautéing for another 2 minutes, until the asparagus is coated and the sauce is well incorporated.
Check doneness
For a crisp-tender texture, the asparagus should turn a bright emerald green and look lightly glossy on the outside.
To test, insert a fork into the thicker bottom end. It should go in with a little resistance. When you bite into it, the asparagus should still have a slight snap. It should not taste raw, mushy, or overly soft.
Taste and adjust
Turn off the heat and taste. Add another pinch of salt if needed.
Serve
Transfer the asparagus to a serving plate and spoon the miso butter pan juices over the top. Serve warm.
Notes
Asparagus thickness: Asparagus comes in different thicknesses, and thicker stalks need a little more time to cook through.
Thin spears: 3 to 4 minutes
Medium spears: 4 to 5 minutes
Thick spears: 5 to 6 minutes
Hybrid steam-sauté method: For extra thick spears, you can briefly cover the pan to help them cook through faster. After adding the miso-stock mixture, cover the pan for about 2 minutes. Shake the pan from time to time. This helps soften the center without overcooking the outside.
Heat control: Keep the pan warm but not too hot. If the pan gets too hot, the butter and miso can burn and taste bitter.