Quick Pickled Onion: Slice the red onions thinly. Combine the onion slices with pickling ingredients in a bowl and let sit for 30 minutes until the onions soften. Drain before using. (You can work on chopping and prepping the rest of the salad, while you wait for the onions)
Shake the Dressing: In a jar, combine the dressing ingredients and shake well until mixed.
Assemble the Salad: In a large bowl, combine the chopped tomatoes, cucumbers, drained and rinsed chickpeas, chopped bell peppers. and drained pickled onions.
Dress and Serve: Pour the dressing over the salad and toss everything together well. Transfer to a serving plate, crumble feta cheese on top, and serve immediately.