Slice the sausage and brown in in a large pan. Drain the salsa, reserving the juice in a small bowl (you want about 1/3 of a cup, discard any more than that). Add the beans and corn to the pan. Whisk the flour into the reserved salsa juice.Add salsa juice/flour to pan, and stir until thickened. Voila–you're done! Serve with grated cheddar on top.