For the orange zest salad, blanch the strips of zest in boiling water three times to remove the bitterness. Drain the zest thoroughly and set aside on kitchen paper.
Mix the salad leaves with the orange segments. Set aside.
For the lobster and mango, blanch the lobster in boiling salted water, two minutes for the tails and three minutes for the claws.
Remove the lobster meat from the shells, cut the tail in half and remove the claws.
In a pan, warm the butter until foaming, drop in the lobster and heat through, basting all the time. Season, to taste, with salt and lemon juice.
Remove the lobster from the pan and add the mango slices to the butter. Cook until the mango is soft and warm. Reserve the butter.
For the orange zest salad, place the zest in a small frying pan with the sugar. Heat until the sugar is caramelised and coats the zest. Set aside to cool slightly, them mix with the vinegar and oil. Pour over the salad leaves and toss to coat.
Place the dressed salad in the centre of serving plates with the lobster around the side and mango on top. Drizzle the butter over and garnish with mustard cress.