
Preheat the oven to 400°F (204°C).
Place the onion and garlic in a food processor and pulse until fully chopped. Transfer to a large bowl.
Add the ground beef, tomato paste, Greek yogurt, ground cumin, paprika, red pepper flakes, kosher salt, and black pepper to the bowl. Mix well using your hands until thoroughly combined.
Divide the mixture into 3 equal pieces. Roll each piece between two sheets of parchment paper into a rectangle. Roll the meat with the parchment paper into a log and place on a sheet pan.
Add the tomatoes and green peppers to the sheet pan. Drizzle with olive oil and season with salt and pepper. Bake for 20 minutes.
For the sauce, melt the butter in a saucepan over medium heat. Stir in the tomato paste and hot water, cooking until it boils. Remove from heat.
To assemble, spread a tablespoon of sauce on a piece of lavash, add meat, roasted vegetables, and Sumac Onions. Drizzle with more sauce, roll up, and cut in half to serve.
