Toast the pine nuts in a dry skillet and transfer to a plate.
Rinse the tomatoes, cut 5 into slices and dice the other finely, taking care to remove the seeds. Rinse the cucumber and cut into slices. Rinse the lettuce thoroughly, trim and shake dry.
Peel the onion and finely chop. Rinse the basil, shake dry and chop the leaves finely.
For the dressing, mix the ketchup with the lemon juice and olive oil and season with salt and cayenne pepper.
Arrange the sliced tomatoes, cucumber and lettuce on a plate. Shower with pine nuts, onions, diced tomatoes and basil and serve drizzled with the dressing.