Fill measuring cup to 1/3 with ketchup. Add sweet pickle juice to make 1/2 cup. Add soya sauce. Stir together and mix into sugar and cornstarch. Add boiling water. Stir well and microwave on high for 2 minutes. Stir and return to microwave for another minute or two, until sauce thickens. Pour over ribs and bake at 350 degrees F for 1 hour.