Make the dipping sauce
Combine the mirin, miso, ginger, carrot juice, orange juice, soy sauce, vinegar, red pepper flakes, and sesame oil in a small bowl, whisking until everything is fully dissolved. Set aside.
Prepare the tuna and serve
Combine the black and white sesame seeds in a shallow dish and press the tuna steaks into them, turning to coat each side.
Heat the oil in a medium sauté pan over medium-high heat. Cook the tuna on both sides until the white seeds have browned slightly, about 30 seconds per side. Transfer the tuna to a paper towel–lined plate for a minute to drain and cool.
Cut each tuna steak into ¼-inch-thick slices and serve with the dipping sauce and chopped cilantro, if using.
Variation
To make vegan
Substitute the tuna with 1 to 2 blocks of extra-firm tofu. To prepare the tofu, place the blocks on several layers of paper towels; cover with more paper towels and top with a cutting board to drain excess liquid. Let stand for several minutes, pressing down occasionally. Cut into serving-size portions.
Serving Suggestion
The tuna is delicious served with cold asparagus or a watercress salad. Serve with Sriracha on the side.
Nutrition information per serving: Calories: 315.9, Total Fat: 11.1g, Cholesterol: 65.7mg, Sodium: 473.8mg, Total Carbohydrates: 16.4g, Dietary Fiber: 2.1g, Sugars: 5.4g, Protein: 37g