Place the chimichurri ingredients into a blender and blitz the parsley, cilantro, olive oil, lemon juice, garlic, dried oregano, chili flakes, salt and pepper together.
Place lamb in a shallow dish. Coat in marinade and cover for four to eight hours or overnight.
Preheat the grill to high heat.
Slice the sweet potato into coins, about 1/4 inch thick. Drizzle with oil and season wtih salt and pepper, then toss to coat.
Cut the tip and base off of the eggplant. Slice into 1/2 inch thick slices. Drizzle in oil and season with salt and pepper. Using your hands or a brush, coat the slices evenly in oil.
Place the sweet potatoes on the grill and cook for three to five minutes.
Flip the potatoes and add your eggplant. Allow to cook for three to four minutes.
Flip the eggplant once you have char marks and the eggplant starts to soften. Remove with the potatoes when they are soft and fudgy. Remove the eggplant when it's well charred and very soft.
Remove the vegetables and allow to cool.
Remove the lamb from the marinade. Place on the grill and cook for three to four minutes a side for medium rare or until the internal temperature is 125 degrees F and allow to rest.
Place the cooled vegetables into a blender. Add garlic, chickpeas, lemon juice, salt, and pepper. Blend until smooth.
Spoon the hummus onto a plate.
Top with chilli oil and a few reserved chickpeas before serving with lamb.