Fill a 12-inch skillet with water about an inch deep. Add a teaspoon of the salt and bring to a boil over high heat. Add the asparagus in a single layer and cook until bright green and just tender, about 1 1/2-2 minutes. Drain and run cool water over them to stop the cooking. Lay them out on a layer of paper towels, then place on a serving platter. Set aside. In a small bowl, whisk together the lemon juice, vinegar, mustard and remaining salt. Drizzle in the oil and whisk until emulsified. Whisk in the garlic. Drizzle the vinaigrette over the asparagus, and serve.