Add all the ingredients for the chickpeas to a bowl and stir to combine. Let marinate while you prepare the rest of the ingredients.
Make the dressing. Put all the ingredients (EXCEPT FOR THE OIL) into a bowl, whisking until they are combined. Slowly add the oil as you continue whisking, until the dressing is emulsified. Taste and adjust seasonings, adding more salt and pepper if necessary. If using a small blender, you can use the same process as above.
Add the lettuce, cucumbers, peppers, tomatoes, feta and onion to a large bowl. Toss with marinated chickpeas and desired about of salad dressing.
Divide among four bowls.