Heat your oven to 400ºF. Add the sweet potato to a sheet pan and drizzle with oil. Season with salt and pepper and roast for 20 to 25 minutes or until golden and tender, stirring halfway through.
Heat a large pot or Dutch oven over medium heat and add in a little olive oil along with the onions and celery. Season with salt and pepper and cook, stirring frequently, just until the onions begin to soften, about 2 minutes. Add in the garlic, ginger, and turmeric and continue to cook for an additional minute.
Pour in the chicken broth and increase the heat to high. Bring the broth to a boil then stir in the orzo and cook for 6 minutes. Meanwhile, remove the meat from the rotisserie chicken. Discard the skin and dice or shred the meat into bite-sized pieces.
Add the chicken into the pot along with the kale and continue to cook for 3 to 4 minutes or until the orzo is cooked through.
Stir in the parsley, lemon juice, and roasted sweet potatoes and season with additional salt and pepper, to taste. Serve the soup topped with some sliced chilis, if using, and serve.
