Along with garlic and anchovies, Nicoise olives are integral to Provencal cuisine. They have an appealing nuttiness and are especially delicious in a vinaigrette tossed with white beans and pear tomatoes and then served over peppery arugula.
Make vinaigrette: Combine olives and the water in the bowl of a food processor fitted with the metal blade. Process until olives are finely chopped. Add garlic, basil, vinegar, and cumin; process until mixture is smooth and combined, stopping to scrape sides of bowl with a rubber spatula as needed.
In a medium bowl, combine beans, tomatoes, and red onion, and gently toss. Pour vinaigrette over bean mixture, and toss well to coat. To serve, divide arugula leaves among four plates, and mound bean mixture on top.
This colorful salad can also be served family-style in a large bowl; toss the arugula in the vinaigrette along with the beans and tomatoes, and let everyone help themselves.