To the bowl of a stand mixer fitted with the paddle attachment, add the cream cheese, halibut, and jalapeño. Mix on low-medium speed until combined, about 60 seconds. Season the mixture with salt to taste.
To assemble the wontons, place a shallow bowl of water on your work surface. Take one wonton wrapper, dip the tip of your finger into the bowl and wet two edges of the wonton wrapper. Place 1 1/2 teaspoons of the halibut filling into the middle of the wrapper. Fold the wrapper over into a triangle and seal the edges securely. Repeat with the remaining wrappers and filling.
Heat the oil in a dutch oven over medium-high heat until it reaches a temperature of 325-350 degrees. Add the wontons to the hot oil, working in batches, and fry 1-2 minutes until golden and crispy. Transfer to paper towels to drain. Repeat with remaining wontons.
Serve promptly with Thai sweet chili sauce.