Heat 1 tablespoon (15 ml) coconut oil (or vegetable or avocado oil) in a 12-inch skillet over medium heat.

Add the finely diced medium yellow onion (about ½ cup). Sauté until the onion starts to soften, about 2 minutes.

Add the sliced bell pepper and the chopped green beans (2-inch pieces). Cook, stirring, for 1 minute.

Add the minced garlic, grated ginger, and the diced chilies (if using). Sauté, stirring, for 30 seconds.

Add 2 tablespoons red curry paste, 1 teaspoon ground turmeric, ½ teaspoon ground cumin, and ½ teaspoon ground coriander. Sauté, stirring, for 30 seconds. If the paste sticks or the pan looks dry, add a splash of water and scrape any browned bits from the pan to deglaze.

Pour in the 14-ounce (400 g) can of full-fat coconut milk, 1 tablespoon (15 ml) fish sauce, and 1 teaspoon coconut sugar (or light brown sugar). Stir to combine, bring to a gentle simmer, and cook until the sauce is smooth and slightly thickened, about 3–4 minutes.

If needed, cut the 1 ½ pound (680 g) fish fillets into 2-inch chunks. Gently add the fish to the simmering curry, reduce heat if necessary to maintain a gentle simmer, cover, and poach for 4 minutes, or until the fish reaches an internal temperature of 145°F (63°C) and flakes easily.

Remove the skillet from the heat, drizzle with the fresh lime juice from 1 large lime, and stir once to combine.

Sprinkle with 2 tablespoons chopped fresh cilantro and 2 tablespoons chopped fresh Thai basil (optional). Serve warm over cooked jasmine rice.