For the red sauce: Combine the tomatoes, onions, parsley, thyme, cumin, celery salt, kosher salt and white pepper in a saucepan. Cook, stirring, for 1 hour. The sauce should be reduced to about 1 1/4 cups. Add more salt and pepper to taste, if needed.
Heat oil in a deep-fryer or a large, heavy pot to 375 degrees F.
Lay the wrappers on a flat clean surface. Blend the cheese and 1/4 cup red sauce in a bowl to create the stuffing. Blend the cornstarch and 1/4 cup water in another bowl, mixing well to create a slurry. Brush the edges of the wrappers with slurry, then place a dollop of sauced cheese in the center of each wrapper. Bring the edges of the wrappers towards the center in a cone shape, and then pinch and seal the bottom edge over to create a triangle.
Fry the pockets until golden, 3 minutes, and then remove with a slotted spoon and allow excess oil to drip over paper towels. Sprinkle with Parmesan and serve over remaining red sauce.