Prepare the Crockpot Add the chicken breasts (or thighs) to the bottom of the crockpot.
Build the Base Pour in coconut milk and chicken broth. Stir in red curry paste, garlic, ginger, fish sauce, lime juice, brown sugar, and onion. Mix until well combined.
Add Veggies Add sliced bell pepper and mushrooms (if using) on top.
Slow Cook Cover and cook on low for 6-7 hours or high for 3-4 hours, until the chicken is fully cooked and tender.
Shred Chicken Remove chicken, shred it with two forks, then return it to the crockpot. Stir well.
Final Seasoning Taste and adjust with salt, pepper, lime juice, or more curry paste if needed.
Serve Ladle into bowls and garnish with fresh chopped cilantro and a splash of Sriracha if you like it spicy. Serve hot!