To make the mayonnaise, whisk the egg yolks with the mustard and some salt and pepper together in a large bowl. Trickle in a few drops of oil, whisking vigorously.
Continue to whisk in the oil, little by little at first, then slowly increasing the amount to a steady stream. Make sure each addition is well incorporated before you add any more. Finally, add a few drops of the truffle oil, if using, then finish with the lemon juice. Keep in the fridge until needed.
Prepare the lobster and remove the meat from the claws and tail. Trim the frayed bit of meat from the tails and flake the claw meat into large chunks, discarding the membrane. Set aside. Cut the tails into 6 slices each and set aside.
Trim the ends off the beans and cut the beans in half. Tip into a bowl with 3 tbsp of the olive oil and season with salt and pepper.
Mix in the lobster claw meat and squeeze over a lemon half, then set aside.
Heat 1 tbsp olive oil in a non-stick frying pan. Fry the potato slices over a medium heat for 5 mins on each side until crisp and golden. Use a fish slice to transfer them to a plate lined with kitchen paper.
Heat 1 tbsp olive oil in the same pan and lower the heat, add the slices of tail meat to the pan, then heat through in the oil for a few moments on each side.
Turn off the heat, season lightly with salt and pepper and squeeze over the lemon. Moments before you are ready to plate up, toss the salad leaves with the balsamic vinegar and remaining olive oil. You are now ready to plate up.