1/2 medium red onion, thinly sliced
1 pound tomatoes, preferably with a combination of colors, cut into bite-sized chunks
2 tablespoons red wine vinegar
1 clove garlic
Flaky sea salt
1/4 cup extra-virgin olive oil
1 medium red bell pepper, seeded and cut into 1-inch pieces
1/3 medium English cucumber, thinly sliced
1 cup kalamata olives, pitted
1/4 cup coarsely chopped fresh dill
1/4 cup fresh mint leaves, coarsely chopped
1 cup crumbled feta cheese
Freshly ground black pepper
Place the onion in a bowl of cold water and set aside 10 to 15 minutes. Meanwhile, cut the tomatoes into bite-sized chunks and place in a medium bowl; set aside. Place the vinegar, garlic, and a pinch of salt in a large bowl. While whisking constantly, drizzle in the olive oil and whisk until combined.
Drain the onion and pat dry with paper towels. Add the red onion, bell pepper, cucumber, olives, dill, and mint to the dressing and toss to combine. Set aside to marinate for 10 minutes. Add the tomatoes and feta and toss gently to combine. Taste and season with more salt and pepper as needed.
Using a slotted spoon, transfer the salad to a serving platter, leaving the juices behind. Serve immediately.