1 hothouse cucumber, unpeeled, seeded, and sliced 1/4-inch thick
1 red bell pepper, large-diced
1 yellow bell pepper, large-diced
1 pint cherry or grape tomatoes, halved
1/2 red onion, sliced in half-rounds
1/2 pound feta cheese, 1/2-inch diced (not crumbled)
1/2 cup calamata olives, pitted

For the vinaigrette:
2 cloves garlic, minced
1 teaspoon dried oregano
1/2 teaspoon Dijon mustard
1/4 cup good red wine vinegar
1 teaspoon kosher salt
1/2 teaspoon freshly ground black pepper
1/2 cup good olive oil