Season and sear. Toss the chicken with garam masala and salt. Heat the oil in cast iron over medium-high and sear the chicken in a single layer, in batches, until browned on the outside (it doesn't need to cook through; it finishes in the sauce). Remove to a plate.
1½ lb boneless, skinless chicken breast, 1 to 2 tsp garam masala, ½ tsp salt, 1 Tbsp avocado oil
Build the sauce. Lower the heat to medium. Add the curry paste to the pan and stir about a minute, until fragrant. Whisk in the coconut milk (and cream, if using), peanut butter, and fish sauce until smooth and glossy. Simmer gently a few minutes to marry.
2 to 3 Tbsp Thai red curry paste, 14 oz coconut milk, ⅓ to ½ cup natural peanut butter, 1 to 2 Tbsp fish sauce, 1 Tbsp brown sugar or honey
Simmer it together. Return the chicken and any juices to the pan. Simmer 8 to 12 minutes, until the chicken is cooked through and the sauce coats the back of a spoon. Stir in lime juice; thin with a splash of water if it's too thick. Taste and adjust salt, heat, and lime.
Juice of ½ to 1 lime
Serve over jasmine rice, showered with cilantro.
Cooked jasmine rice, Chopped fresh cilantro