Heat the oil in the large skillet. Add half the drumsticks and cook until the skin is golden brown, about 8 minutes. Remove and discard the skin for the remaining drumsticks.

Add the chicken, celery, carrots, cilantro stems, onion, lemongrass, jalapenos, garlic, ginger, and peppercorns to your slow cooker. Cover with water. Cook on low for 12 hours.

Remove the chicken and shred; set aside.

Strain the stock through a fine mesh strainer lined with cheesecloth. Discard the solids. Season with salt and pepper.

Add the shredded chicken back into the stock. Bring to a boil and add the zucchini noodles; cook 2-3 minutes, or until cooked through.

Allow each diner to garnish their soup with cilantro, basil, jalapeno slices, and Thai chili sauce to taste.