Start by prepping ingredients: dice the onion, mince the garlic, and mince the ginger. I peel the ginger with a spoon or vegetable peeler and then finely mince it. Thinly slice the red bell pepper into long vertical strips and then cut those strips in half horizontally.
Heat 2 tablespoons coconut oil in a large deep skillet over medium-high heat. Add the onion and saute for 3-5 minutes or until onions are beginning to get golden. Add the garlic and ginger. Stir to coat everything with the oil. Lower the heat to low and add in the curry powder, red curry paste, and coriander. Stir often for 2-3 minutes or until lightly toasted and fragrant.
Return the heat to medium high. Add in the remaining 1 tablespoon coconut oil and the red pepper. Stir for 1-2 minutes and then add in the bite-sized pieces of chicken. Sprinkle on salt and pepper to taste (I add 1 teaspoon fine sea salt and 1/2 teaspoon pepper). Cook, stirring often for about 4-5 minutes or until the chicken is browned on both sides, but not cooked through.
Pour in the coconut milk, lime juice, and brown sugar (to taste; I start with just 1 tablespoon). Stir until chicken is cooked through (juices run clear and it is cooked to 165 degrees F) and curry is slightly thickened (Note 1). If desired, stir in the fish sauce.
Serve over rice and/or with naan bread. Garnish individual plates with cilantro, basil, and/or crushed peanuts/cashews. Serve additional lime wedges by the side if desired.
Note 1: If you want a thicker sauce, you can remove 1-2 tablespoons of the sauce to a small bowl and (with a fork) whisk in 1 tablespoon cornstarch until smooth. Whisk this mixture into the curry.