Slice the trimmed tuna into 25 g rectangles. Peel and julienne the ginger into fine strips. Marinate the tuna in sesame oil (or palm or soybean oil), ginger, and sesame seeds for 1-2 hours.
Blend softened butter with anchovies and black pepper to make anchovy butter. Chill until ready.
Line mini bowls with lollo rossa leaves. Top each with a tuna piece and ginger slice. Drizzle with marinade oil. Add a quenelle of anchovy butter in the center, then sprinkle with chopped chives and sesame seeds.
Expert Tips: Keep anchovy butter chilled and quenelle just before serving. Select firm, blood-free tuna to avoid stringiness.