Remove the meat from the lobster, keeping the claw meat in one piece, and cut up the tail. Keep the shells for the sauce.
For the pasta, mix the flour and semolina together on a clean work surface or in a large bowl. Make a well in the centre and break in the eggs. Using a fork or your hands, gradually mix the flour with the eggs to form a soft dough. Knead the dough for 5 minutes, or until smooth.
Shape the dough into a ball, wrap in cling film and leave to rest in the fridge for at least 30 minutes.
For the sauce, heat a frying pan to medium hot. Add the butter, shallot, fennel, lobster shells and star anise and fry for a couple of minutes, or until softened but not browned.
Add the wine and cook until the volume of liquid has reduced by half. Add the fish stock and cook until reduced by half again. Add the cream and cook until reduced by one-third.
Strain the sauce through a sieve, the stir in the tomato and herbs. Taste and season with salt and freshly ground black pepper.
Once the pasta has rested, divide it into 4 equal pieces. You can roll them out by hand using a rolling pin, or use a pasta machine.
To roll by hand, dust with semolina and use a rolling pin to roll out each piece, working slowly and dusting the pasta with semolina as you go to avoid tearing it.
Alternatively, dust a pasta machine with semolina and starting at the lowest (thickest) setting, feed one piece of the dough through the machine, turning the handle with one hand and holding the dough as it comes through the machine with the other. Change the setting on the pasta machine to the next-thickest setting, flour it again and feed the pasta sheet through the machine again, as before.
Repeat this process 3-4 more times, flouring the machine and changing the setting down each time. The pasta should be quite thin, but still easy to handle without tearing. Don't be tempted to skip settings or the dough may tear. Repeat with the other pieces of dough.
Once the pasta sheets have reached the ideal thickness, set aside and dust with semolina.
To make the tortellini, use a circular cutter to make circles of pasta 9cm/4in in diameter. Place a piece of the tail meat on each circle. Brush a little water on the edge of the pasta and fold over the top to make a semi-circle. Press down lightly to seal. Wrap the corners of the semi-circle around your index finger and join together to make a tortellini shape. You need 6 tortellini per person.
For the garnish, heat a large frying pan and once hot add the butter and oil. Add the courgette balls and cook for a couple of minutes, or until the courgettes have a little colour on them.
To cook the pasta, bring a large saucepan of salted water to the boil. Add the pasta and simmer for 3-5 minutes until cooked, then drain immediately.
To serve, place 6 of the tortellini in the centre of each serving bowl and spoon over the sauce. Garnish with the lobster claw meat, the courgette balls and cress.