Preheat oven to 450°F. In a large covered saucepan, bring water to a boil over high heat for orzo.
Meanwhile, in a large bowl, combine chicken, egg, parsley, bread crumbs, garlic, oregano, salt and pepper. With this mixture, make 24-28 bite sized meatballs (about 1-inch in size).
Place meatballs on a large rimmed baking sheet, lined with parchment paper. Brush meatballs lightly with 1 tablespoon olive oil or spray with olive oil spray. Bake for 7-10 minutes or until cooked through (165°F internal temp).
While meatballs are in the oven, prepare the orzo according to package directions. Drain well and dump into a large bowl. Toss orzo with beans, spinach, and feta.
Prepare dressing in a small bowl by whisking together lemon juice and remaining 3 tablespoons olive oil. Pour over orzo and toss to combine.
Divide salad between four plates. Top with meatballs, sprinkle with cucumber and tomato, and serve immediately.
Make ahead tip: Cooked meatballs can be made a day or two in advance. Refrigerate in a covered container. Reheat lightly before adding to salad.