Spray a large, nonstick skillet with nonfat cooking spray (I like the Pam butter-flavored kind for this recipe) and set over medium-high heat.
Season tilapia fillets with salt and pepper and place in pan.
Sear each side of the tilapia for about 3 minutes. Then turn the heat to medium. Pour in the entire bottle of salad dressing. Cover and let cook for about 15 minutes, or until fish is cooked through, making sure to occasionally spoon dressing over fish while cooking.