Heat a tablespoon of neutral oil in a large pot over medium heat. Add finely chopped shallots and the white parts of scallions, sautéing for about 2-3 minutes until softened and fragrant. Stir in a pinch of salt to enhance their flavor, watching the shallots turn translucent.

Add the choo chee curry paste to the pot, stirring well to combine. Fry the mixture for another 2-3 minutes until the paste is fragrant and slightly darkened. Then, pour in the solidified fat from the can of full-fat coconut milk, allowing it to melt and blend with the aromatics.

Once the paste is ready, gradually pour in the remaining coconut milk and your choice of water or chicken stock. Increase the heat to bring the mixture to a gentle boil, stirring occasionally to ensure everything is well incorporated.

Incorporate sliced carrots and bell pepper into the boiling mixture. Lower the heat to a simmer and cover the pot, cooking for about 20 minutes until the vegetables are tender yet still have a slight crunch, absorbing the rich flavors of the choo chee fish curry.

After the vegetables have softened, stir in the fish sauce, tasting as you go to adjust the seasoning to your preference.

Pat the mahi mahi filets dry and season them lightly with salt. When the curry reaches a steady boil again, gently place the fish into the pot. Cover the pot and let it simmer for 5-8 minutes until the fish is cooked through and reaches an internal temperature of 145ºF.

Carefully transfer the cooked fish and vegetables into serving bowls, ladling the luscious curry sauce over the top. Serve with cooked white rice or rice noodles, garnishing with fresh Thai basil leaves, lime wedges, minced cilantro, and crispy shallots for an extra touch.