Cook the pasta in salted boiling water. Drain, and drizzle with a little olive oil to prevent sticking. Put aside to cool slightly.
In a food processor, add the avocado, cucumbers, feta, half of the arugula, pesto, salt and lemon juice. Process until very smooth.
In a large bowl, combine the pasta and the dressing, and toss well. Add the tomatoes and the remaining half of the arugula; toss again. Transfer to a picnic dish, top with the toasted pine nuts, and garnish with some basil leaves.
This recipe is great without the nuts, if you're allergic. If you're not fond of or are allergic to avocado, then substitute 1/3 cup cream cheese.