In a small bowl, mix the olive oil, vinegar, salt, black pepper, onions and garlic together. Let it sit for 10 to 15 minutes.
Slice the tomatoes into wedges. If you are using grape or cherry tomatoes, slice them in half.
Add the tomatoes, cucumbers, olives, feta cheese, chickpeas and chopped herbs to a large bowl. Pour the vinaigrette on top and toss the salad to combine the ingredients together. Taste and season with more salt or pepper, if necessary.