Step 1

Prepare grill for medium-high. Whisk lemon zest, Meyer lemon zest, lemon juice, Meyer lemon juice, mustard, and ¼ cup oil in a medium bowl to combine; season dressing with salt and pepper (if you don’t have Meyer lemons, use regular lemons in their place).

Step 2

Place asparagus and spring onions on a rimmed baking sheet and lightly drizzle with oil. Season with salt and pepper; toss to coat. Grill, turning once, until lightly charred and crisp-tender, about 4 minutes. Serve drizzled with dressing.