Mix all ingredients and tie into cheesecloth bag. Hang over bowl in refrigerator for 2 days. Over the course of 2 days, very gently squeeze to help drain water.
Prior to serving, remove from cheesecloth and whisk. Add olive oil if thinner consistency is desired. Season with salt and pepper. Hold for service.
To prepare the Chile Sauce:
Toast chiles, red pepper flakes, and cumin seeds in a dry small skillet over medium heat, tossing occasionally, until fragrant and cumin seeds are golden, about 3 minutes. Let cool. Working in batches, finely grind in spice mill, then transfer to a blender.
Add vinegar, paprika, and garlic to blender and blend until smooth. With motor running, gradually stream in oil and blend until combined. Transfer to a large bowl; season with salt. Hold for service.
To prepare the Meatballs:
Pulse onion, chopped garlic, parsley, oregano, sage, fennel seeds, coriander, cumin and salt in a food processor, scraping down sides as needed, until finely chopped. Add egg, lamb, and flour and pulse until evenly combined. Form lamb mixture into 1-in. balls.
Heat 2 Tbsp. oil in a large skillet, preferably cast iron, over medium-high. Working in 2 batches and adding another 1 Tbs. oil to skillet if needed, cook meatballs, turning occasionally, until browned on all sides and cooked through, 5-8 minutes. Transfer meatballs to paper towels to drain.
Transfer all meatballs to bowl with chile sauce and toss to coat.
To prepare the Cucumbers:
Toss cucumber in a medium bowl with lemon zest and juice, vinegar, olive oil and season with salt and pepper.
To serve:
Spoon labneh onto shallow plate, top with 3-4 meatballs and arrange dressed cucumbers. Garnish with mint and sprinkle of chili flakes.
