How to Grill Tuna Steaks: Step by Step
Step 1: Prep Your Grill
Cleaning and oiling a preheated grill grate: an essential step for any grilled recipe, but especially fish
Setting up your grill for tuna steaks follows the same basic best practices for grilling anything else. You want to preheat your grill and grill grate, clean the grate well with a grill brush, and finally oil the grate. A hot, clean, and oiled grill grate will be much less likely to severely stick to your fish than a gunky, cold one.
Because you want to sear your tuna steaks as quickly as possible to minimize the amount of heat penetration, you’ll be cooking over the hottest coals possible. You can set your grill up as a one- or two-zone fire, depending on what else you’re cooking. There’s little chance you’ll need a cooler area on the grill to finish your tuna: as soon as it’s seared on both sides, it’s done.
Step 2: Prep the Tuna Steaks
Before grilling tuna steaks should be dried well with paper towels as shown in the photo at left; then it should be lightly rubbed with oil and seasoned with salt (photo at right)
While your grill is preheating, you can prep your fish. It’s important to dry the fish well on both sides, using paper towels—minimizing surface moisture helps speed the searing process along and reduces the chances of the tuna sticking to the grill.
To that end, I also like to lightly rub the dried steaks with a neutral oil like canola or vegetable oil. It’s just one more bit of insurance against sticking.
Step 3: Grill the Tuna
Salt draws moisture out of proteins like fish and other meats, so I make sure to sprinkle it on the tuna at the last second. After we’ve made sure to dry the surface of the fish well, the last thing we want to do is get it wet again before putting it on the grill.
Set the tuna steaks over the coals. Your goal here is to get a sear on the exterior as quickly as possibly, while minimizing how much heat penetrates to the center. Even with all of the preparations we’ve made, the fish will still likely stick to the grill grate at first, so do your best to refrain from attempting to lift or move the steaks prematurely. They should release on their own once they’ve browned well.
To flip a piece of fish on the grill, like the tuna shown here, it helps to insert the prongs of a carving fork or large kitchen tweezers down between the slats of a grill grate, then lift from below
If the fish has adhered to the grill grate at all, the best way to release it isn’t to try to force a metal spatula underneath. Instead, slide a thin metal tool, like the tines of a carving fork, large culinary tweezers, or even the spatula blade itself, down between the grill grates and under the fish. Then gently lift from below, being careful not to force it if it’s stuck on tight.
Because of how rare I think grilled fresh tuna should be served, I don’t bother with thermometers. There’s nothing to measure: Just sear both sides and then pull it off the grill right away.
A piece of grilled tuna still on the grill: the top side is already cooked, but you can see from the side that the fish is still almost totally raw in the center; heat is creeping up from below, and you can see the flesh on the bottom side starting to turn an opaque tan color, markedly different from the luminous raw beefy purple still visible around the edges.
Still, I understand that people want a little more guidance than just that. What I recommend is to watch the edges of the tuna steak. Tuna is remarkable among fish in that its color change from raw to cooked is so dramatic. Raw tuna is a deep, dark purple-red hue, but once heat touches it, it comes a light beige. By observing the sides of the steak you can get a sense of just how far the heat is reaching into it. Just keep in mind that because heat will swirl up and around each steak, the exterior edge will still cook more quickly than the interior, so it’ll begin to shift towards beige before the inside does.
When it’s done, remove it from the grill and slice it with the sharpest knife you have, ideally a thin-bladed one like a slicing knife. I think it’s good simply drizzled with fresh olive oil and a sprinkling of salt and fresh black pepper.
No matter how you serve it, remember that there’s no rush. Because the tuna is so rare in the center, it’s not really something that starts out all that hot in the first place—it’s just as good at room temperature, or even cold.