Mince the garlic cloves and slice the ginger into thin matchsticks. Thinly slice the onion into 1/4-inch half-moons and dice the red bell pepper into bite-sized pieces. Pat the shrimp dry with paper towels—this is crucial for getting a good sear and preventing them from steaming. Heat 1.5 tablespoons of oil in a large pan over medium-high heat until shimmering, then add the shrimp in a single layer. Sear for about 1 minute until mostly opaque, then transfer to a clean bowl. The shrimp will finish cooking later in the curry, so don't worry if they're not completely cooked through at this stage.

Add 1 tablespoon of oil to the same pan over medium heat. Add the minced garlic and sliced ginger, stirring constantly for about 30 seconds until fragrant—this blooms the aromatics and develops the curry's flavor foundation. Add the red curry paste and stir well to combine, cooking for 1 minute. I like to give the paste time to caramelize slightly in the oil, which deepens its spice complexity and reduces any raw paste taste.

Stir in the brown sugar, sliced onion, and diced bell pepper from your mise en place. Cook for about 2 minutes, stirring occasionally, until the onion begins to soften and the vegetables start to release their moisture. The sugar will help balance the heat of the curry paste and add subtle sweetness.

Pour in the coconut milk and stir well to incorporate all the curry paste and spices into the creamy base. Bring the mixture to a gentle simmer over medium heat and let it cook for about 2 minutes. This allows the flavors to meld together and the sauce to thicken slightly. The bubbling coconut milk will help the vegetables finish cooking and create a silky, cohesive sauce.

Return the seared shrimp from Step 1 to the pan and gently stir to coat them in the curry sauce. Simmer for 1 minute until the shrimp are heated through and fully cooked. Add the fish sauce and taste the curry—season with salt as needed. I always add fish sauce at the end rather than the beginning because it's pungent and its flavor can intensify during cooking. Transfer to serving bowls and garnish generously with fresh cilantro.