Cut the reserved tilapia into 1/2-inch chunks and put them into a glass bowl. Top with the onion, tomato, and jalapeno. Pour in the orange and lime juices and stir gently to mix. Cover and refrigerate for 1 hour. Don't let it marinate longer or the fish will turn mushy.
While the fish is marinating, heat the oven to 350 degrees F. Spray a baking sheet lightly with cooking spray. Cut the tortillas into 6 wedges and spread them on the baking sheet in 1 layer. Bake in oven until lightly browned and crisp about 12 to 15 minutes. Sprinkle with salt.
Serve the ceviche in small bowls garnished with the cilantro and with the tortilla chips on the side.
Recipe courtesy of Sandra Lee