Place all of the lemon grass, 250g of the caster sugar and the chopped mint leaves in a non-stick deep frying pan; pour over 150ml water, place over a medium heat and bring to the boil
Reduce the heat and simmer for 10-15 minutes until thickened; strain into a bowl, reserving the halved lemon grass stalks, set aside
Peel and core the pineapples, then cut into 1cm thick slices; sprinkle the slices with the remaining sugar
Brush a large frying pan with the oil and place over a medium heat; working in batches, cook the sugared pineapple slices for 4-5 minutes, on each side, until lightly caramelized
Transfer the pineapple slices to a flat serving dish and sprinkle over the pomegranate seeds; pour the lemon grass syrup over the fruit and garnish with the reserved stalks.