For the mousse: Soak gelatine in a little cold water. Separate eggs. Whisk egg yolks with sugar until fluffy, add lemon juice and zest and mix well. Dissolve gelatine in a small saucepan on low heat. Add to the egg yolks and mix well. Beat egg whites until stiff and fold into the mixture, refrigerate for 2 hours.
Place sugar in a saucepan and caramelize slowly on medium heat. Peel fruit and cut into wedges. Drizzle fruit with some caramel and arrange on plates. Place lemon mousse pieces on top and drizzle with remaining caramel in thread-like pattern. Garnish with mint leaves and lemon zest, dust with powdered sugar and serve.