Put the bulgur in a bowl and pour the hot water over it. Let the bulgur swell for about 30 minutes.
Cut the onion into fine strips and mix with the bulgur. Roughly chop the parsley (be sure to buy it from a Turkish grocery store, as the amount is based on a Turkish bunch of parsley) and mix with the bulgur.
Now squeeze the lemons. Mix the lemon juice from one lemon with the oil and season with salt and pepper. Pour this marinade over the tabbouleh. Finely dice the tomatoes and mix in as well. Let the salad stand for about 1 1/2 hours before serving. Season to taste again before serving and mix in more lemon juice if necessary.