Slice the celery hearts. Tip the olive oil, lemon juice and 1 teaspoon of pepper into a bowl and stir.
Cook the tortelloni for 2 minutes in a large pot of salted boiling water. Strain delicately with a skimmer and tip them into the bowl along with 2 tbsp of pasta cooking water and celery. Mix delicately, divide between 2 plates, garnish with the salmon roe, sprinkle with chopped celery leaves and the remaining pepper and serve.