Heat vegetable oil in a large skillet or wok over medium-high heat.
Add chicken pieces and cook for 5 minutes until browned on all sides, then remove from the pan and set aside.
In the same skillet, add the diced onion and sauté for 3 minutes until translucent.
Stir in the minced garlic, grated ginger, and red curry paste, cooking for 1 minute until fragrant.
Pour in the coconut milk, fish sauce, and brown sugar, stirring to combine and bringing the liquid to a gentle simmer.
Return the chicken to the skillet and add the red bell pepper and snap peas.
Simmer for 5 to 7 minutes until the chicken is cooked through and the vegetables are tender-crisp.
Remove from heat, stir in the lime juice, and garnish with fresh cilantro before serving.