Add about 1 tablespoon olive oil to a large saucepan or dutch oven over medium-high heat. Add in onion, garlic, ground lamb, and spices. Break up ground lamb with spoon and stir to evenly incorporate spices.
olive oil, ½ yellow onion, 3 cloves garlic, 1 pound ground lamb, 2-3 teaspoons kosher salt, ½ teaspoon black pepper, ½ tablespoon ground ginger, ½ tablespoon cinnamon, ½ tablespoon cumin, ½ tablespoon smoked paprika, ½ teaspoon coriander, 1 teaspoon chili powder, ½ teaspoon turmeric, 1-2 tablespoons brown sugar, crushed red pepper
Remove ground lamb from pot and add a bit more olive oil followed by chopped collard greens and diced sweet potato. Saute for about three minutes then add add back cooked ground lamb plus crushed tomato, broth, and mushrooms to pot.
2 cups beef broth, 28 ounces crushed tomatoes, 3-4 collard green leaves, 1 sweet potato, 3 baby bella mushrooms