Greek Salad Horiatiki

Name: Greek Salad (Horiatiki)
Ingredients: 2 tablespoons red wine vinegar; 1 1/2 teaspoons dried oregano, preferably Greek; 1/4 teaspoon kosher salt, plus more as needed; 1/4 teaspoon freshly ground black pepper, plus more as needed; 1 clove garlic; 1/4 cup extra-virgin olive oil; 1 large English cucumber or 4 Persian cucumbers; 1 large green bell pepper; 1 pint cherry or grape tomatoes; 1 small red onion; 6 to 8 ounces block feta cheese, preferably Greek; 6 sprigs fresh mint (optional); 2 tablespoons drained nonpareil capers (optional); 1/3 cup pitted kalamata olives