Cook the pasta in boiling salted water according to the package directions. Rinse with cold water and drain.

Place the pistachios in a dry skillet and cook over medium-high heat until fragrant, 3- 4 minutes. Let cool and coarsely chop.

Place the tahini, water, lemon juice, olive oil, garlic, ½ teaspoon salt and ¼ teaspoon pepper in a blender and process until smooth.

Peel the cucumber, slice in half lengthwise, scrape out the seeds with a spoon and cut into ¼ inch slices. Place the cucumber slices in a large mixing bowl, add the garbanzo beans, onion, olives, tomatoes, pasta and dressing. Toss to combine. Taste, and add more salt and pepper if needed. Add the mint leaves, pistachios and feta and gently toss to combine. Refrigerate until serving.