When there's a huge sale at Stew's on wild-caught yellowfin tuna... resistance is futile.
For years, one of our big splurge meals has been a riff on the tuna "filet mignon" from the original Union Square Cafe Cookbook. I've changed the marinade a bit, but the essentials have remained the same. Here's a link to the original...
https://cooking.nytimes.com/recipes/3441-union-square-cafes-marinated-filet-mignon-of-tuna
Because I never keep teriyaki sauce in the house, I marinate the tuna in soy, sherry, garlic, cayenne, and scallions. (Trust me, you won't miss the teriyaki.) In the olden days, I grilled this on an indoor tabletop "smokeless" grill given to me by the extraordinary Deb Stenard. Now I just heat up a grill pan until it threatens to catch fire!
I'm going to suggest that you just sear the outside... and have almost sushi within... but that's totally your call.
We savored this treat topped with A Lot of pickled ginger, along with a side of mashed potatoes and some peas and salami quickly sautéed in olive oil, salt, and pepper...
And fond memories of our (much) younger days.
Try this sometime. I know we shouldn't eat tuna frequently until their situation improves, but every now and then... Sigh.