Make the Harissa mayonnaise by whisking together mayonnaise and harissa powder. Cover and refrigerate until ready to use.

To make the burgers combine lamb, onion, garlic, oregano, cumin and salt together in a bowl. Mix well.

Divide the meat into four even sections. Roll and then gently flatten into patties.

Heat a skillet over medium heat.

Place lamb patties in preheated pan and cook until browned and cooked through, about 3 - 4 minutes per side.

White patties are cooking, toast hamburger buns under the broiler.

To make a burger: Place the burger on the bottom bun, top with lettuce. Spread a generous layer of harissa mayonnaise on top bun. Repeat with remaining ingredients until 4 burgers are made. Serve.