In the bowl of a food processor mix the garbanzo beans, onions, egg, gruyere cheese, oregano, garlic and 1 tablespoon olive oil. Mix until you reach a thick paste. Transfer to a bowl and add the breadcrumbs. Season with salt and pepper and let it rest for 10 minutes.
Meanwhile prepare the tahini sauce by adding all the ingredients in a bowl and season to desired taste.
Slightly wet your hands and grab one spoonful of the garbanzo mix. Roll it and then slightly flatten. You can also use an ice cream scooper, roll and flatten.
In a large skillet heat, add the remaining 2 tablespoons olive oil and fry the croquettes 2 minutes approximately on each side. Transfer to a paper towel to drain any oil excess.