In a large bowl mix altogether: dry bulgur, chopped pasley, diced tomatoes, onion, lemon juice, olive oil, sumac, salt and pepper.
With a vegetable corer remove the insides of the zucchinis. Then fill them with the tabbouleh and bulgur mixture until 3/4 full only leaving space for the bulgur to expand when cooked.
In a pot, place the sliced onion and tomato. Add the stuffed zucchinis, the tomato paste and cover with water. Cook on high heat until it starts boiling then lower the heat with the pot covered and let it simmer for about 25 minutes.
Slice the cooked zucchinis and serve with a cup of low fat yogurt and decorate with parsley leaves and halved cherry tomatoes.
One serving of this recipe includes 10 zucchinis and a cup of yogurt.