Pre-heat oven to Gas 6, 200°C, fan 180°C.
Cook the lobster in a large pan of boiling water. Check the cooking time for this, as it will vary, depending on the size of the lobster.
Meanwhile, finely slice the shallots, ginger, chilli and lemon grass. Heat 1tbsp olive oil in a pan over a medium heat and sauté the shallots and spices, taking care not to burn them.
Drain the lobster when it is cooked and let it cool before removing the shell and reserving the meat in the fridge for later. Add the shell to the pan with the shallots. Add the white wine to the pan and bring to the boil then reduce the heat and simmer gently for 20 minutes.
Now it is time to prepare the potato crust. Begin by cutting 2.5cm (1in) cylinders out of the potatoes. One large baking potato should be sufficient for each portion. Slice each cylinder into very thin, even slices.
Melt 50g (1½oz) unsalted butter in a small bowl and beat in the cornflour to make a smooth paste. Add the potato slices to the bowl and, with your fingers, carefully turn them in the mixture to get an even coating.
Bring a small pan of water to the boil and blanch the washed and trimmed asparagus for 3-5 minutes, depending on the thickness of the stalks. Remove from the heat and plunge the asparagus stalks into ice-cold water to retain their colour and bite. Set aside.
Add the cream and 2 lime leaves to the sauce pan and reduce the volume of liquid by half.
While the sauce is reducing, wash your halibut steaks under running water and pat them dry. Place them on a board and carefully arrange the potato slices on top of each steak in neat, overlapping rows so that they resemble fish scales.
When the liquid has reduced, strain the contents of the pan through a fine sieve and return the smooth, infused cream to a small saucepan on a very low heat. This will be finished just before serving.
Heat a non-stick frying pan on a high heat. Place the halibut steaks in the pan, potato side down, for 2-3 minutes, until the potato is crisp and golden. Carefully transfer them to an oven tray and place in the preheated oven for 5 minutes. Check the steaks are cooked through before serving.
While the fish is in the oven, place the asparagus in the same frying pan to heat through and add the chopped lobster meat for 30 seconds. Arrange on your serving plates in a single layer.
Remove the lime leaves then whisk 25g (1oz) butter into the sauce along with the juice of half a lemon. Add this to the serving plates.
Remove the halibut from the oven and place on top of the lobster and asparagus then serve immediately.
Please note: this recipe has been created and uploaded by a member of the Tesco Real Food online community. Tesco does not test customer recipes so cannot accept responsibility for the content, validate the results or answer queries regarding them.