Finely slice the onion and carrot. Remove seeds and white filaments from the bell pepper and finely slice.: The aroma of thinly sliced onion hitting warm oil should be sweet and slightly pungent, while the carrot releases a subtle sugary scent. Visually, the vegetables will glisten and become slightly translucent at the edges, which tells you they are softening. This step matters because even cooking ensures the vegetables meld into the sauce instead of staying raw. A common mistake is cutting pieces unevenly, which leads to some bites being overcooked and others underdone. Keep sizes consistent so everything finishes at the same time.
Remove skin from both the hake and trout, cut into chunks and set aside. Also remove the coral from the scallops and set them aside.: Fresh fish should smell clean and mild, not fishy, and when you cut chunks you will see firm flesh and glossy surfaces. Removing the skin prevents curling and uneven cooking, while taking out scallop coral leaves a sweeter center for even searing. This matters because uniform pieces cook at the same rate, preserving texture. Avoid overcrowding when you later add seafood, because crowding cools the pan and causes steaming rather than a quick sear.
Heat a large wok or cast iron skillet with the olive oil over medium heat. Add in the garlic, ginger, whole chilli pepper, onion, bell pepper, carrot, pak choi and snow peas, and stir-fry for 2 minutes.: When the oil warms, it should shimmer and release a faint tobacco aroma, and the garlic and ginger will perfume the pan almost immediately. You will hear a lively sizzle as vegetables hit the skillet, and their edges will start to color slightly, which is the visual cue you want. Stir-frying on medium keeps vegetables crisp tender rather than limp. A frequent error here is cooking on too low heat, which causes sogginess, or too high heat, which burns aromatics. Keep motion steady, tossing every few seconds so nothing blackens.
Add in the Thai red curry paste and sugar and cook for another minute.: The paste will darken slightly and bloom in the oil, releasing fragrant chili, lemongrass, and spice notes, while the sugar quickly begins to melt into a glossy sheen. This blooming magnifies flavor, making the paste taste rounder and less raw, which is crucial to a balanced curry. If you skip this, the paste can taste flat. Watch carefully because pastes can stick and scorch, so stir constantly during this brief step.
Move the vegetables over the sides of the wok, and add into the center the hake and trout fillets, followed by the scallops and mussels, and stir-fry for 1 minute.: When seafood hits the hot center, you should hear a different, brisker sizzle and see immediate firming at the edges, signaling the Maillard reaction starting. The contrast between the lightly cooked vegetables around the rim and the seafood in the center helps the proteins sear without overcooking. This technique matters because a quick, high heat contact preserves juicy interior texture. Avoid stirring constantly in the first moments, or the seafood will not get the initial sear that locks in moisture.
Pour in the coconut milk and fish sauce, and add in the lemongrass. Cook for 5 minutes, then remove the lemongrass and whole chilli pepper. If it's too thick, add a splash of water, and adjust seasoning to taste.: As the coconut milk pours, it will hiss softly and create a creamy pale pool that contrasts with the red curry, and steam will carry a rich, sweet aroma. Gentle simmering lets the flavors marry and the seafood finish cooking through, while the lemongrass infuses citrusy top notes. Removing aromatics prevents bitterness from over‑extraction. If the sauce reduces too far, a splash of water keeps the texture silky. A common mistake is leaving lemongrass too long, which can make the broth fibrous and overly potent.
Remove from the heat, squeeze half lime over the curry, and sprinkle with fresh coriander on top.: The lime should hiss slightly as its juice meets the warm sauce and lift the whole flavor profile, brightening the coconut and cutting residual richness. The torn or chopped coriander scattered on top adds a green, peppery perfume and visual freshness. This finishing acidity is essential for balance, or the curry may feel one note heavy. Avoid using too much lime, which can flatten the curry; a measured squeeze is enough.
Serve immediately with steamed jasmine rice on the side.: The final dish should be hot and aromatic, with steaming rice absorbing the saucy curry. Jasmine rice provides a fragrant cushion and neutral base so each spoonful highlights the curry components. Serving right away preserves the ideal textures, because seafood can become rubbery if held too long. Do not let the curry sit uncovered, or it will cool and lose vibrancy.