1: Prepare the lime custard (crème anglaise): proceed as for the usual recipe, but with these proportions: 3 egg yolks, 250 ml Milk, and 35 g caster sugar, don't forget to add zest of 1 lime to milk before boiling.
2: Once the custard is made, cover and leave to cool.
3: Peel 3 grapefruits, you need about 6 segments per guest. Place the segments on a rack over a plate, sprinkle with sugar, and leave at room temperature. This is so that the grapefruit does not produce too much juice when the dessert is finally assembled.
4: Peel 1 Pineapples, cut into quarters lengthways, then into slices approximately 1/2 cm (1/4 inch) thick. You should obtain 6 pieces by guest.
5: Just before serving, divide grapefruit segments between serving plates.
6: Melt 30 g butter in a frying pan, clarified if possible. Add the pineapple and brown while stirring frequently. When the pieces are golden, add 2 tablespoons brown sugar, and allow to melt and caramelize, stirring occasionally.
7: Put a piece of pineapple beside each grapefruit segment.
For complete success in this recipe there should be a contrast between the cold grapefruit and custard, and hot pineapple. If you don't have citrus crunch, you could add a pinch of cococa powder instead, and/or flaked almonds.