Chopped Veggie Salad with Watermelon and Feta Cheese

1 lb campari (plum tomatoes diced drained)

1 12 cups watermelon (diced seeded)

1 green bell pepper (seeded cut into 13 inch cubes)

12 hothouse cucumber (english, seeded cut into 13 inch cubes)

12 cup radishes (thinly sliced)

3 tbsps olive oil (divided)

10 ozs feta cheese (broken into small cubes about 2 12 cups divided)

2 green onions (chopped divided)

14 cup mint leaves (thinly sliced fresh, divided)

12 cup plain greek style yogurt

1 tsp dried oregano

1 whole yogurt (thick yogurt; sold at some supermarkets and at specialty foods stores such as trader joe s and whole foods markets and greek markets if unavailable place regular, strainer set over large bowl cover and chill overnight to drain)