- 4 tablespoons unsalted butter, softened
- 1/2 teaspoon wasabi powder or fresh wasabi paste
- 1/4 teaspoon freshly ground white pepper
- 1 tablespoon chopped fresh chives
- 1 teaspoon fresh lemon juice
- Salt and freshly ground black pepper, to taste
- 1 cup raw sesame seeds
- 4 (6 ounce) tuna steaks
- 2 tablespoons vegetable oil
- In a large bowl, combine the butter with the wasabi, white pepper, chives, and lemon juice with a fork. Whisk until smooth; season with salt and black pepper. Form into a log about 3 inches long and 1 inch thick. Wrap in waxed paper; tightly turn down and tape ends to seal. Refrigerate until firm, at least 1 hour. (The butter can be made up to 2 days in advance).
- Place the sesame seeds in a large shallow bowl. Season the tuna with salt and pepper, and then roll in the seeds to coat evenly on all sides.
- Pour the oil into a nonstick skillet large enough to hold the tuna steaks in a single layer without crowding. Heat over high heat until almost smoking. Add the tuna and cook until the seeds start to turn golden on the bottom, about 1 minute. Carefully turn and cook for another minute or two, or until the seeds are golden brown. Do not overcook the fish.
- Cut the butter into 4 thick slices. Transfer the tuna to warmed serving plates and top each with a slice of the butter.