Bring the pasta water to the boil. Add a generous amount of salt. Cook the spaghetti until crispy.
Meanwhile, make the tomato and basil salad; chop the cherry tomatoes, tear the basil and toss in a bowl with the ingredients as directed. Leave to marinate.
When the pasta is done, carefully pour off the cooking water and stir in the red pesto.
Roll the spaghetti onto plates and garnish the edges of the dishes with the tomato and basil salad.