In a food processor, puree onions and garlic with 2 tablespoons olive oil. Transfer to a container.
Blend the Italian green peppers and red bell pepper in the food processor and add it to the onion and garlic.
Blend parsley and tomatoes in the food processor and mix it with the onion and pepper mixture.
Add the ground lamb and ground beef to the mixture and mix until well combined.
Add in tomato paste, the remaining olive oil, Aleppo pepper, black pepper, cumin and salt. Mix well.
Cover and refrigerate for at least 1 hour up to 24 hours.
Meanwhile, make the dough by mixing water and salt in the bowl of a stand mixer.
Attach the dough hook and start mixing, add in the flour, ½ cup at a time until the dough forms and it doesn't stick.
Divide the dough into 12 pieces and place them on a baking sheet. Cover with a kitchen towel and let it rest for 30 minutes.
Heat a non stick skillet with the lid on over medium heat and place the topping container on the counter top next to the pan and give it a stir.
Take one of the dough balls and keep the rest covered with a kitchen towel. On a floured surface, roll out the dough into a very thin circle no bigger than the pan.
Transfer the dough into the hot pan and adjust it. Spread a thin layer of topping on the crust using a serving spoon and leave ½ inch from the edges.
Put the lid on and cook for 7-8 minutes until the dough and the topping are cooked. The dough will be crispy.
Repeat with the remaining dough and topping.
Top cooked lahmacun with tomatoes, parsley and squeeze some lemon juice and season with sumac. Wrap it and serve.