In a large skillet, heat 1 tablespoon of the safflower oil until shimmering. Add the sliced ginger, shallots and garlic and cook them over moderate heat until softened, about 3 minutes.

Add the red grapefruit, orange and lemon juices along with the wine, light soy sauce and stock and bring to a boil over high heat. Cook until the sauce is reduced to 1/2 cup and is slightly syrupy, about 40 minutes.

Set a fine-mesh sieve over the jar of a blender. Strain the sauce, pressing on the solids to extract the liquid. With the blender on, slowly pour in the remaining 3/4 cup of oil until combined.

Alternatively you could thicken the sauce with a bit of cornstarch (about 1 tbs in some cold water) and reduce the fat content of the recipe

Light a grill or heat cast iron griddle. Lightly brush the tuna steaks with oil and season with salt and pepper. Grill the steaks over moderately high heat, turning once, until medium rare, about 6 minutes.

Transfer the steaks to plates, spoon the sauce on top and serve with the wasabi on the side.

Adapted from Recipe by Ann Chantal Altman