To prepare filling, heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add onion and bell pepper; sauté 5 minutes or until onion begins to brown. Stir in tomato, red pepper, and 1/4 teaspoon salt; sauté 2 minutes. Stir in Beef Carnitas; cook for 2 minutes, stirring frequently. Remove from heat; cool to room temperature.
Preheat oven to 400°.
To prepare dough, combine 9 tablespoons water and saffron; cool to room temperature. Stir in vinegar. Lightly spoon flour into dry measuring cups; level with a knife. Place flour, baking powder, sugar, and salt in a food processor; pulse 2 times to combine. Add butter; process until mixture resembles coarse meal. With processor on, slowly pour saffron mixture through food chute; process just until dough begins to form a ball (dough will be crumbly).
Divide dough into 2 equal portions. Working with one dough portion at a time, press dough into a 4-inch circle on heavy-duty plastic wrap. Cover with additional plastic wrap. Place dough in freezer 5 minutes or until plastic wrap can be easily removed.
Slightly overlap 2 sheets of plastic wrap on a slightly damp surface. Unwrap 1 dough portion; place on plastic wrap. Cover dough with 2 additional sheets of overlapping plastic wrap. Roll dough, still covered, into an 11-inch circle. Repeat procedure with remaining dough. Place both portions in freezer for 5 minutes or until plastic wrap can be easily removed.
Remove plastic wrap from 1 dough portion; place dough, plastic wrap side up, on a large baking sheet coated with cooking spray. Remove top sheets of plastic wrap. Spoon filling onto dough, leaving a 1-inch border. Remove top sheets of plastic wrap from remaining dough. Place dough, plastic wrap side up, over filling. Remove top sheets of plastic wrap. Pinch edges together to seal. Cut several slits in top of dough to allow steam to escape. Bake at 400° for 30 minutes or until crust is crisp and beginning to brown. Cut into 8 wedges.