For the ponzu dressing: In a saucepan
over medium heat, combine the soy sauce, sugar, katsuobushi and rice wine vinegar. Simmer
until the sugar
is dissolved and the sauce is reduced by half. Set aside to cool. When sauce is cooled, add the lemon juice
juice and zest and orange juice
For the beef and green onion rolls: Trim the green onions into 6-inch lengths. Slice the beef tenderloin into six 1/8-inch-thick slices (1 1/2 to 2 inches wide). Pound the beef slices between two sheets of plastic until flattened.
Place a piece of the pounded beef on a cutting board and sprinkle with pepper. Place three pieces of green onion across the beef slice, so the onions extend over the edges. Roll the beef up and set it in a glass baking dish
. Repeat with remaining beef and green onions. Pour half of the ponzu dressing
over beef rolls and marinate for 5 to 10 minutes.
Preheat a grill or grill pan
until hot, or prepare the oven broiler. Grill the beef and green onion rolls, turning, until slightly charred and medium rare, about 2 minutes. Remove from heat and keep warm.
For the shishito peppers: Toss the peppers in the olive oil. Grill over high heat, searing until slightly blistered, 2 to 3 minutes. Remove from the grill, sprinkle with the lemon juice, and toss to coat. Season with salt.
To serve: Plate the beef rolls atop shiso leaves. Garnish with sesame seeds and green onions, and serve with the grilled shishito peppers and the remaining ponzu dressing.