Heat a wok or large skillet over medium-high heat until. Add 1 tablespoon of oil, and spread it around to coat. Add the shrimp, and allow it to sear for 30 seconds on 1 side. Then stir-fry for 30 seconds, until the shrimp is 75% cooked (it should be mostly opaque). Turn off the heat, remove the shrimp to a bowl, and set aside.
Over medium heat, add the remaining tablespoon of oil to the pan, along with the garlic and ginger. Fry for 30 seconds, until fragrant. Increase the heat to medium-high, add the curry paste, and fry for another minute. Stir in the brown sugar. Then add the onion and pepper, and fry for 2 minutes.
Add the coconut milk. Bring to a simmer over medium-high heat. (From this point on, keep the curry at a simmer. Avoid boiling it too vigorously, or the coconut milk may split and have a grainy appearance.) Simmer for 2 minutes to thicken the sauce and cook the onions down.
Stir in the shrimp, and simmer for 1 more minute. Taste and season with additional salt if needed (particularly if you used less curry paste). Garnish with cilantro if desired, and serve!
Notes
Nutrition information calculated using 1 entire can of curry paste.