In a large pot, heat the vegetable oil over medium heat. Add the diced onion and sauté until translucent, about 5 minutes.
Stir in the minced garlic and grated ginger, cooking for an additional 1-2 minutes until fragrant.
Add the red curry paste and cook for another minute, stirring to combine.
Pour in the coconut milk and chicken or vegetable broth, stirring well. Bring the mixture to a gentle simmer.
Stir in the fish sauce and lime juice, then add the shrimp, mushrooms, red bell pepper, and snap peas. Cook for about 5-7 minutes, or until the shrimp are pink and cooked through.
Taste and adjust seasoning if necessary. Serve hot, garnished with fresh cilantro and lime wedges on the side.