Velvet the chicken: In a bowl, toss the 1 ½ pounds boneless skinless chicken thighs with 1 tablespoon cornstarch ½ teaspoon baking soda, 1 teaspoon olive oil, salt and black pepper. Let sit for 10-15 minutes while you prepare the potatoes.
Heat a large skillet over medium-high heat. Add 1 tablespoon oil and the 1 diced sweet potato. Cook for about 5 minutes, stirring occasionally, until the potato starts to brown.
Add 2 tablespoons water and cover for 3-5 minutes. Once mostly tender, transfer to a plate.
Add the remaining oil to the pan. Add the chicken in a single layer and let it cook undisturbed for 2–3 minutes.
Add 1 onion and 1 jalapeño and cook another 3–4 minutes until the vegetables softened and the chicken is browned with slightly crisp edges.
Add the 2 tablespoons tomato paste, 3 cloves garlic, 1 tablespoon fresh ginger, 1 teaspoon smoked paprika and ⅛ teaspoon cinnamon. Cook for 1–2 minutes until the tomato paste darkens slightly.
In a bowl or measuring cup, whisk together ⅓ cup peanut butter, ¾ cup chicken broth, 1 teaspoon brown sugar, and 1 teaspoon Worcestershire sauce. Pour into the pan and stir to coat the chicken.
Return the sweet potatoes to the pan and simmer for 2–3 minutes until the sauce thickens.For the best texture, let the mixture sit undisturbed for 30–60 seconds at a time between stirring so the sauce caramelizes slightly onto the chicken. Serve over rice, topped with cilantro and peanuts, if deseired.