Combine chicken, lime juice, and 1 tbsp curry powder in a large bowl, and toss to combine; refrigerate for at least 4 hours or up to overnight.
Melt oil or butter in a good stew pot or wok. Add remaining curry powder, the allspice, garlic, scallions, thyme, carrots, sweet potato, and ginger, and cook, stirring occasionally, until lightly caramelized, about 6 minutes. Add chicken and any remaining marinade to pot along with coconut milk and chile, and stir to combine. Cook, stirring occasionally, until chicken is cooked through and sauce is thickened, about 40 minutes; add soy sauce and creme fraiche to taste. Serve over rice.
This is an often-NSFW, mostly gluten-free kitchen notebook that also occasionally threatens to turn into something else and fails, thus remaining its same old cryptic and superficial self. These posts begin to fail to explain (start at the bottom).