Layer the sweet potatoes and bell peppers in the bottom of a 5-quart (or larger) slow cooker. Drizzle the water and lime juice evenly over the top.
In a small bowl, mix together the curry powder, smoked paprika, cumin, chili powder, and salt. Lay the chicken thighs on a large plate or cutting board, then sprinkle about two-thirds of the spice mixture over both sides. Rub the spices into the chicken to coat evenly, and reserve the remaining spice blend.
In a large skillet, heat the olive oil over medium-high heat until it’s hot and shimmering. Add the chicken thighs and sear them briefly, about 2 minutes on the first side and 1 minute on the other, until browned.
Transfer the seared chicken to the slow cooker, placing it on top of the vegetables. Sprinkle the remaining spice mixture over the chicken. Cover and cook on LOW for 4 to 5 hours or on HIGH for 2 to 3 hours, until the chicken is thoroughly cooked and reaches an internal temperature of 165°F when checked with an instant-read thermometer.
Take the chicken thighs out of the slow cooker and place them on a cutting board. Once they are cool enough to handle, cut the chicken into bite-sized pieces or shred it using two forks. Set the chicken aside.
Add the coconut milk and cornstarch slurry to the slow cooker, stirring to mix with the vegetables and cooking liquid. Set the slow cooker to HIGH, cover, and cook for 15 minutes, allowing the sauce to thicken slightly.
Place the chicken back into the slow cooker and mix it well to ensure it’s evenly coated in the sauce. Cover the cooker and let it cook on HIGH for another 15 minutes, allowing the chicken and vegetables to heat through and become tender. Enjoy.