Slice the lotus root into 1cm half-moon pieces and soak in water. Drain well.

Remove bones from the mackerel and cut into bite-sized pieces.

Place lotus root, cherry tomatoes, and 1 tsp salad oil into a plastic bag. Seal and mix to coat evenly.

Mix white sesame seeds, miso, and mayonnaise in a bowl to make the sesame miso mayo sauce.

Line a baking tray with aluminum foil and brush with salad oil. Place mackerel skin-side up, then add lotus root and cherry tomatoes. Bake in a toaster oven for 7–8 minutes until vegetables are slightly browned.