Trim the ends of the asparagus, then slice the stalks on a steep diagonal into 2-inch-long pieces and put them into a bowl. Cut the carrot into slices a scant 1⁄4-inch thick and 2 inches long; this ensures they’ll cook at the same rate as the asparagus. If using mushrooms, cut the stems and caps into 1/3-inch-thick slices or tear into large bite-size pieces. Add to the bowl of asparagus.
Set a 14-inch wok or 12-inch nonstick or carbon-steel skillet over high heat on one of your largest burners and swirl in the neutral oil. When the oil ripples, toss in the ginger and garlic. Rapidly press down and stir them to release their aroma. Dump in the vegetables and sprinkle with the salt. Stir and toss for about 1 minute, until the vegetables look glossy with brighter color.
Spread out the vegetables to cover the pan bottom, add the water, cover, and then reduce the heat to medium-high. Let the veggies steam-cook 2 minutes, stirring midway and spreading them out again. When the boiling sounds start turning into a crackling noise (which signals water evaporation), uncover and quickly flip and stir the vegetables, about 1 minute, until no more liquid remains. If needed, turn the heat to high to hasten cooking and thus prevent overcooking. If the vegetables are too firm, add a splash of water and cook 1 to 2 minutes longer. When the veggies are done, they should look lightly glazed. Transfer to a plate or shallow bowl, discard the ginger and garlic if you spot them, and serve immediately.