How to Make It
Preheat the oven to 400°. On a rimmed baking sheet, toss the diced sweet potato with the olive oil, paprika and piment d’Espelette. Season with salt. Roast the sweet potato for about 10 minutes, stirring halfway, until golden and tender. Reduce the oven temperature to 350°.
Meanwhile, season the chicken thighs with salt. In a medium enameled cast-iron casserole, heat the canola oil. Add the chicken and cook over moderately high heat until browned all over, about 7 minutes. Transfer the chicken to a plate. Add the mushrooms, garlic, shallots and lemongrass to the casserole and cook, stirring, for 2 minutes. Add the white wine and bring to a boil. Simmer for 2 minutes, stirring to dissolve any browned bits on the bottom of the casserole. Add the chicken broth, heavy cream, fish sauce and Sriracha.
Return the chicken thighs to the casserole and bring to a boil. Cover and braise the chicken in the oven for about 1 hour, until very tender.
Spoon the roasted sweet potato into bowls. Top with the chicken thighs and mushroom sauce and serve.