1 Trim stalks from fennel. Rinse bulbs, dry and cut into thin strips.
2 Peel the potato and cut into 1 cm (approximately 1-inch) cubes.
3 Add diced potatoes to a pot of boiling salted water and cook 7 minutes.
4 After 4 minutes, add fennel strips to the potatoes.
5 Drain the vegetables, run under cold water to stop the cooking and drain well.
6 Meanwhile, rinse lemon in hot water and wipe dry. Finely grate the zest and juice the lemon. Rinse basil, shake dry, pluck leaves and cut into very thin strips.
7 Cut out 6 pieces of foil (each 30 x 30 cm or approximately 12 x 12 inches). Drizzle each piece with 1 teaspoon olive oil.
8 Rinse the halibut, pat dry and place on the foil pieces. Season with salt and pepper.
9 Divide vegetables among fish pieces and season lightly with salt and pepper.
10 Top each portion with lemon juice, lemon zest and basil.
11 Fold up foil into a packet, sealing the edges.
12 Cook packets on a medium-hot grill, without turning, for 10 minutes (fish will be opaque throughout). Open packets carefully before serving.