Warm lobster potato salad with truffled mayonnaise

Name: Warm lobster & potato salad with truffled mayonnaise
Ingredients: 2 cooked lobster, about 500g each; 250g fine green bean, cooked; 2 shallot, finely chopped; 6 tbsp olive oil; 1 lemon, halved; 12 new potato, cooked; 100g mixed baby salad leaf; 1 tsp white balsamic vinegar; 2 egg yolk; 1 tbsp English mustard; 300ml olive oil; few drops truffle oil (optional); juice ½ lemon