Pat the chicken dry and season with salt. In a casserole set over moderately high heat, warm the oil until it is hot, add the chicken and cook it, turning, until no longer pink. Transfer chicken to a plate. Add the onion to the casserole and cook it, stirring occasionally, for 3 minutes. Add the garlic and gingerroot and cook, stirring, 1 minute. Add the carrots, bell pepper, mushrooms, and salt to taste, and cook the mixture, stirring occasionally, for 5 minutes more. Return the chicken to the pan, add the curry paste and cook the mixture, turning and stirring, 1 minute. Add the coconut milk, galanga root powder, lemongrass flakes, cumin, and bay leaf. Bring mixture to a boil, and simmer, stirring occasionally, for 20 minutes. Add the broccoli, bamboo shoots, water chestnuts, corn, and salt to taste, and simmer the mixture, stirring occasionally, for 10 minutes, or until chicken is cooked through. Discard bay leaf. Before serving, stir in the lemon juice, cilantro, and mint.