1 cup mayonnaise
4 teaspoons soy sauce
1 1/2 teaspoons sugar
2 teaspoons fresh lemon juice
2 teaspoons wasabi paste (green horseradish paste), or to taste
a 12-ounce tuna steak, cut into twenty 1-inch cubes
ten 8-inch bamboo skewers, soaked in water 30 minutes
In a bowl stir together mayonnaise, soy sauce, sugar, and lemon juice. Transfer 2/3 cup soy mayonnaise to a small bowl and stir in wasabi paste. Stir tuna into remaining 1/3 cup soy mayonnaise. Chill wasabi mayonnaise, covered, at least 1 hour and up to 24. Marinate tuna, covered and chilled, at least 1 hour and up to 24. Prepare grill. Thread 2 tuna cubes onto each skewer and grill on an oiled rack set 5 to 6 inches over glowing coals until just cooked through, 2 to 3 minutes on each side. Serve tuna sates with chilled wasabi mayonnaise.