Peel the zest from the two grapefruits and then juice. Cut the zest into small 3cm batons. Blanch in boiling water and refresh in ice water – repeat this process three times.
After blanching, put the grapefruit batons into the grapefruit juice.
Add sugar until you reach a balance of sweet and sour. Reduce the mixture to a syrup consistency.
Place the glucose, sugar and water into a pan and bring to the boil. Remove from the heat and add the grapefruit and lemon juice. Churn in an ice cream machine and freeze.
Fillet and dice the mackerel into 1cm cubes. Dice the mooli into ½ cm cubes. Blanch the mooli in boiling salted water for ten seconds and refresh in iced water.
Mix the mackerel with the olive oil, lemon juice, chives and season to taste. Place neatly on the plate. Season the diced mooli with olive oil, salt and pepper. Spoon on top of the mackerel.
Place the watercress and grapefruit confit on top of the mooli. Neatly quenelle the grapefruit sorbet on top and serve.
