Greek-Taverna Salad

Soak onion in cold water 10 minutes; drain. Sprinkle garlic with a pinch of salt; mash into a paste with the side of a knife. Transfer to a large bowl. Whisk in lemon juice, vinegar, mustard, sugar, oregano, mint, 2 teaspoons salt, and 1/4 teaspoon pepper. Slowly whisk in oil.

Add tomatoes, stirring to fully coat in dressing. Top with cucumbers, bell peppers, feta, peperoncini, and onion. Cover and refrigerate up to 1 day. Toss to combine and evenly coat (or shake vigorously, if using a bowl with a resealable lid) just before serving.