In a large heavy bottom skillet or iron skillet, heat olive oil or coconut oil over medium high heat and begin browning the chicken pieces in batches. Place browned chicken into slow cooker.
Place cubed potatoes, carrots, and mixed peppers on top of the meat.
Drizzle about 1 tablespoon more oil into the skillet if needed, and brown the onion; spoon browned onion into the slow cooker with the other ingredients.
Immediately add the curry paste, ginger and lemongrass paste to the skillet and "saute" the paste for about 1 minute.
Stir in 1 can of coconut milk and reduce to medium-low heat and let simmer and reduce by half.
Whisk in chicken broth and remaining can of coconut milk, along with peanut butter. Bring to a boil, then reduce to low and simmer for about 5 minutes.
Pour sauce over ingredients in slow cooker, gently stir ingredients to combine and set to low for about 4 to 6 hours.
About 20 minutes before serving, season to taste with lemon juice, fish sauce and brown sugar.
Stir in half of the chopped peanuts.
Serve with hot cooked rice and sprinkle with additional chopped peanuts.