Put the shallot in a round dish with half the butter.
Micro wave on HIGH for 2 minutes.
Put the fish on top of the chopped shallot and add the Vermouth.
Season with salt and pepper.
Cover and microwave on HIGH for 5 minutes.
Rinse the red bell pepper, seed and remove the pith.
Cut the flesh into thin strips and then into dice.
Put the bell pepper and frozen shrimp (prawns) in a small casserole.
Cover and microwave on HIGH for 4 minutes.
Bring a pan of salted water to the boil on a conventional cooker.
Add the tagliatelle.
Bring back to the boil and cook for 2 minutes.
Drain in a colander.
Put the fish on two plates.
Cover with aluminum (aluminium) foil to keep hot.
To make the sauce: put the remaining butter in a bowl and melt in the microwave oven for 1 minute on HIGH.
Add the flour, stirring constantly.
Add the cooking liquid from the fish and the milk, whisking with a hand beater.
Add the egg yolk, beating vigorously.
Put into the oven and cook for 1 minute on HIGH.
Whisk the sauce again.
Grate the cheese into it and whisk once more.
Taste and adjust seasoning.
Pour the tagliatelle into a serving bowl.
Add the red bell pepper and shrimp (prawns) and stir well.
Put a serving of the mixture on each plate with the fish.