Prepare the Pickled Vegetables: In a small saucepan, combine the rice vinegar, water, sugar, and salt. Heat until the sugar and salt dissolve, then pour over the sliced vegetables. Let sit for at least 30 minutes.
Make the Ginger-Soy Glaze: In a small saucepan, combine the soy sauce, honey, rice vinegar, and grated ginger. Simmer over low heat until the glaze thickens slightly, about 5-7 minutes. Set aside.
Crust the Tuna: Pat the tuna steaks dry with paper towels and season with salt and pepper. Press the sesame seeds onto both sides of the tuna, ensuring an even coating.
Sear the Tuna: Heat a skillet over high heat and add the oil. Once the oil is hot, sear the tuna for 1-2 minutes on each side, until the sesame seeds are golden and crispy, and the tuna is cooked to your desired level of doneness.
Slice and Plate: Let the tuna rest for a few minutes before slicing into thick slices. Arrange on a plate, drizzle with the ginger-soy glaze, and serve with the pickled vegetables on the side.
Garnish and Serve: Garnish with fresh herbs, extra sesame seeds, and a final drizzle of glaze if desired.