Combine salt and fennel seeds in a mortar and pestle and pound until fine. Stir cumin, cinnamon, coriander, turmeric, and garlic cloves into the salt mixture and continue grinding to form a thick paste. Stir in harissa sauce and tomato paste until combined.
Combine ground lamb and the spice paste together with a fork in a large bowl. Cover and refrigerate overnight.
Form sausage into patties. Heat olive oil in a large skillet over medium-high heat. Cook patties until no longer pink inside, 5 to 8 minutes per side, depending on the size of the patties.