For the fish: Cut tilapia into bitesized chunks. Place in a bowl. Add the flour and toss to coat. Add the soy sauce. Let fish marinate for 30 min. Heat oil in heavy, deep skillet and sautee fish until golden, about 4 minutes, turning to brown all sides.
For the sauce: Saute green pepper and onion in about 1T of oil for 1 min. Whisk the corn starch into the pineapple juice and stir it and the remaining sauce ingredients into the pan with the vegetables. Cook until thickened, stirring occasionally. Pour the sauce over the fish and toss lightly.
For the salsa: Combine all ingredients and chill until ready to serve.
Serve fish and sauce over rice with the salsa on the side.