Roast the bell pepper on a burner until charred all over, then put in a plastic bag, seal and allow to cool, then peel, de-seed, and coarsely chop. Combine the pepper with the garlic, oil, cumin, cayenne and the smoked paprika in a blender or food processor and puree until very smooth.
Transfer the puree to a small pan and cook on medium heat, stirring constantly for 15 minutes, or until the mixture is deeply caramelized, it’s orange color will change to a deep red. Alternately, the pepper paste can be baked in a 350 degree oven for 20-30 minutes being stirred occasionally, until deeply colored.
Reserve the harissa, you should have about 3 tablespoons of paste. Meanwhile, put the lamb in the freezer for 15 minutes while you allow the paste to cool. The harissa can be made ahead of time and refrigerated.