Cut half of the scallops into thin slices and set aside.
Coarsely chop the rest, and mix with the olive oil, lemon juice, cilantro and red onion. Season and set aside.
In a saucepan over low heat, slightly roast the cereal with sesame oil. Set aside.
Cut the avocados in half. Remove the pits, and slice as thinly as possible. Turn the sliced halves over, so the hollow from the pit is upward. Place each of them on a piece of plastic wrap. Fill the hollows with ceviche, and lift the four corners of the plastic wrap to the centre. Twist the wrap gently to make round balls. Set aside in the refrigerator.
Place the slices of scallops on plates. Remove the balls from their wrapping, and place one of them in the centre of the scallops on each plate. Garnish with the sesame-scented cereal, and drizzle with marinade. Add a sprig of chives or other herb to enhance the presentation.