Slice top and bottom ends off oranges; cut off peel and white pith, following the shape of the fruit. Cut orange segments from membrane to remove and roughly chop. Place in a medium bowl. Discard peel, pith and membrane. Stir in onion, cilantro, chile, salt and 1 tablespoon lime juice.
Sprinkle both sides of snapper evenly with Cajun seasoning. Heat oil in a large nonstick or cast-iron skillet over medium-high heat. Add the snapper; cook until golden brown and cooked through, 3 to 4 minutes per side. Transfer to a plate and flake into large pieces using 2 forks. Sprinkle with the remaining 1 tablespoon lime juice.
Divide the snapper and cabbage evenly among warm tortillas. Top with the orange salsa. Garnish with additional cilantro, if desired.
