Bring water and 2 Tbsp. kosher salt to a boil in a large pot over high. Add pecan halves, and cook until slightly softened, 30 to 45 seconds. Drain pecans, and spread on paper towels; cool 2 minutes. Combine 2 tsp. kosher salt, orange zest, and Chinese five-spice powder. Meanwhile, pour canola oil to a depth of 1 1/2 inches into a Dutch oven. Heat over medium-high to 325°F. Toss together pecans and powdered sugar in a bowl; stir until pecans are evenly coated with sugar and almost all excess sugar is melted. Carefully add coated pecans to hot oil; fry until lightly golden, about 3 minutes. Using a spider skimmer or large slotted spoon, remove pecans to paper towels; drain briefly, about 10 seconds. Transfer hot pecans to a medium bowl, and toss with spice mixture. Cool 30 minutes.