Lentil Chili With Merguez

Name: Lentil Chili With Merguez
Ingredients: Merguez sausage can generally be found at gourmet and cooking supply stores. Harissa can generally be found at gourmet and cooking supply stores, as well as select well-stocked supermarkets.; 3 tablespoons olive oil; 1 large onion, thinly sliced lengthwise; 2 teaspoons chopped ginger; 1 teaspoon chopped garlic; Zest of 2 lemons; 2 sticks cinnamon; 4 teaspoons cumin; 4 teaspoons smoked paprika; 1 tablespoon turmeric; 1 teaspoon cardamom; 1/4 cup tomato paste; Juice of 1 lemon, more to taste; 3 (14.5-ounce) cans diced tomatoes; 2 pounds fresh merguez sausage, casings removed and crumbled; 10 cups chicken broth, divided, plus more as needed; Salt; 2 pounds dried lentils; Pinch saffron, optional; 2 tablespoons harissa paste, or to taste, plus more for garnish; 1/4 cup minced parsley; Chopped cilantro, for garnish; Feta cheese, crumbled, for garnish