For the Slow Cooker Harissa American Lamb: Rub entire surface of lamb with 2 tablespoons harissa paste. 

In a large skillet over medium-high heat, heat oil. Add lamb; brown on all sides until golden brown, approximately 3 to 5 minutes on each side. Transfer lamb to slow cooker; brush with 2 tablespoons harissa paste. 

Return skillet to medium-high heat; add sliced onion. Sauté onions in lamb grease until they just start to soften, approximately 3 minutes. Stir frequently. 

Add sautéed onions and broth to the slow cooker; cook on high for 5 hours, or low for 8 hours. 

Once lamb has finished cooking, transfer to a clean plate to cool. Scoop out cooked onions into a large, clean bowl; set aside. Reserve half the cooking juices leftover in the slow cooker; mix with the final two tablespoons harissa paste. 

Shred lamb using two forks (or your hands); transfer to the bowl with the cooked onions. Pour broth and harissa mixture over shredded lamb; gently stir to combine. Top with chopped cilantro and green onion, if desired; set aside. 

For the Pomegranate Salsa: In a medium bowl add pomegranate arils, green onion, cilantro, oranges, red onion and lime juice; gently toss to combine. 

For the Tacos: Just before serving, add peeled and pitted avocados to a bowl. Use a fork to smash the avocado until creamy, but not quite smooth. Stir in juice from one lime; season with salt and pepper, if desired. 

To serve: Start with a tortilla; add a generous layer of avocado. Top with a scoop of shredded harissa lamb, Pomegranate Salsa, and jicama sticks.