Boil the pasta: Bring a large pot of generously salted water to a boil. Add the linguine and cook until al dente — about 1 minute less than the package suggests. Reserve 1 cup of pasta water before draining.
Prep the prawns: While the pasta cooks, pat the prawns completely dry with paper towels. Season with a pinch of salt and pepper. This step is critical for getting a nice sear instead of a pale, watery mess.
Sear the prawns: In your large skillet, heat 1 tbsp of neutral oil over medium-high heat. Add the prawns in a single layer and cook until golden on one side, about 2 minutes. Flip and cook for another 30-60 seconds until just cooked through. Transfer to a clean plate.
Bloom the aromatics: Reduce the heat to medium. Add 1 more tbsp of oil to the same skillet. Add the garlic and grated ginger, stirring for 30 seconds until fragrant but not brown.
Bloom the curry paste: Add the curry paste. Break it up with a wooden spoon and let it bloom in the oil for about 1 minute until it smells warm and deeply aromatic. This blooming step is non-negotiable.
Build the sauce: Pour in the can of coconut milk, fish sauce, brown sugar, and the juice of 1 lime. Whisk to combine. Bring it to a gentle simmer and let it bubble for 2-3 minutes, letting it thicken just slightly.
Add the pasta: Add the cooked linguine directly to the skillet. Using tongs, toss it in the sauce. Add ¼ cup of the reserved pasta water and keep tossing until the sauce coats every strand. The starch in the water helps the sauce cling and creates that glossy, emulsified texture.
Return the prawns: Return the cooked prawns to the skillet. Toss gently to warm them through.
Finish and serve: Remove from heat. Taste it. Add another squeeze of lime if it needs brightness, or a pinch of salt if it needs depth. Plate it up and garnish with cilantro and chili flakes.