Heat 1 tablespoon coconut oil in a large skillet over medium heat.
Add the chopped onion, minced garlic, chopped mushrooms, and minced ginger; sauté until the onion is translucent, about 5 minutes.
Add the bite-sized chicken pieces and cook, stirring occasionally, until the outside is no longer pink, about 5 minutes.
Stir in 2 tablespoons Thai red curry paste and the sliced red bell pepper; cook for 1–2 minutes until fragrant.
Pour in the 14-ounce can of full-fat coconut milk, 1 1/2 tablespoons fish sauce, and 1 tablespoon brown sugar; bring to a simmer.
Simmer gently for 10–15 minutes until the chicken is cooked through and the sauce has slightly thickened.
Stir in 1 tablespoon lime juice, taste and adjust seasoning if needed, then serve over cooked jasmine rice and garnish with chopped cilantro.
