Prepare the Fillings: Warm the grilled Unagi fillet slightly, then cut it lengthwise into long, even strips. Peel the ripe avocado and slice it into uniform strips.

Prepare for Rolling: Wrap your bamboo sushi rolling mat securely in plastic wrap to prevent sticking. Place a half-sheet of Nori seaweed rough-side up on the mat.

Spread the Rice: Wet your hands lightly. Spread an even layer of seasoned sushi rice over the entire surface of the Nori. Sprinkle toasted sesame seeds evenly over the rice.

Flip and Fill: Carefully flip the Nori over so the rice is facing down against the bamboo mat. Lay the strips of warm Unagi and sliced avocado horizontally across the center of the bare Nori.

Roll and Serve: Using the bamboo mat, lift the bottom edge and roll it tightly over the fillings, tucking it in to create a firm cylinder. Squeeze the mat gently to shape the roll. Remove the mat, slice the roll into 8 pieces using a wet knife, and drizzle heavily with sweet eel sauce before serving.