Roast pumpkin seeds in a pan without fat. Wash lemon hot, grate dry and cut in half. From one half cut off 2 thin slices, squeeze juice. Use the remaining half for other purposes.
Cut the avocado in half, remove the core. Remove the flesh from the skin and cut into cubes. Wash the tomatoes and cut into cubes, except for something to garnish. Mix prepared ingredients and yoghurt mixture and season with lemon juice.
Arrange in a glass. Garnish with lemon wedges and tomato.