Satay Ayam Chicken Satay

Name: Satay Ayam (Chicken Satay)
Ingredients: 1⁄3 cup peanut oil; 1⁄4 cup dark brown sugar; 1 tbsp. ground coriander; 2 1⁄2 tsp. ground turmeric; 1 1⁄2 tsp. ground fennel; 1 1⁄2 tsp. kosher salt; 6 stalks lemongrass, trimmed and chopped, plus 1 stalk, whole; 3 cloves garlic, peeled; 3 large shallots, chopped; 1 (5″) piece ginger, sliced; 3 1⁄2 lb. skinless chicken thighs, cut into 1″-wide, ¼”-thick slices; 30 (8″) bamboo skewers, soaked in water for 30 minutes