Fry the mushrooms in a little vegetable oil and season with salt and pepper.
Bring the lentils to the boil in the vegetable stock and simmer for 4 minutes on a low heat. Remove from heat, let cool down a little and mix in the ingredients for the dressing. Season to taste with salt and pepper.
Divide the rocket on 2 bowls and cover with the mushrooms. Spread the lentil dressing over the top and sprinkle 1 tablespoon of seeds over the salad.