Step 1

Heat a gas or charcoal grill. Turn a gas grill to high or fill a chimney and light the charcoal. Dump the hot, ashy briquettes in the center of the grill grate. Rub a little vegetable or canola oil on the grate to prevent the fish from sticking.

Step 2

Season the opah with olive oil, salt, and pepper. Set 2 opah fillets (3⁄4 pound (340 g) total) on a plate and season the fish on both sides with 1/2 teaspoon (2.5 ml) of olive oil. Sprinkle both sides of the fish with salt and pepper to taste.

Step 3

Toss the asparagus with olive oil, garlic powder, salt, and pepper. Put 1 pound (450 g) of trimmed asparagus in a long dish. Drizzle it with the remaining 2 teaspoons (10 ml) of olive oil and sprinkle the asparagus with 1/8 teaspoon (0.25 g) of garlic powder, and salt and pepper to taste. Use a spoon or your fingers to mix the asparagus so it's evenly coated.

Step 4

Grill the seasoned asparagus for 4 to 5 minutes. Lay the seasoned asparagus across the grill grate so the pieces don't fall through the grate. You could also lay the asparagus in a grilling basket that's set directly on the grill. Grill the asparagus for 4 to 5 minutes, so it softens and blackens a little.Grilling baskets are metal containers that are square or circular. They have holes and handles, so you can fill them with food and set them directly onto the grill grate. Buy grilling baskets at the hardware or grocery store.

Step 5

Grill the opah with asparagus for 2 to 3 minutes. Use tongs to flip the asparagus over and lay the seasoned opah on the grill. Cook the asparagus for 2 to 3 minutes.

Step 6

Flip and grill the opah and asparagus for 2 to 3 more minutes. Use the tongs to flip the fish and let it cook on the other side for 2 to 3 minutes. Both sides of the fish should be cooked while the inside will be medium-rare.If you prefer your fish to be medium, grill the opah for another 2 minutes. Check for doneness by scraping a fork against the center of the fish. The fish will become dry and flaky in the center.

Step 7

Remove the grilled opah and asparagus and serve. Once the opah is as cooked as you like, transfer it to a serving plate. Remove the asparagus and place it on the serving plate with the fish. Serve the fish with freshly squeezed lemon juice and steamed rice.Store the leftover fish in an airtight container for 3 to 4 days.