MagisterCultuum
Great Sage
You could just not bother with districts, but use at large vote with proportional representation.
Alternately you could go so far as Professor Bernardo de la Paz suggested in The Moon is a Harsh Mistress (which I just read last week) and forgo elections entirely in favor of selecting representatives by petition, possibly giving representatives unequal voting power based on the number of their supporters. That way no congressman would represent any minority that opposes his policies, and all minority groups could select alternative representatives.
Alternately you could go so far as Professor Bernardo de la Paz suggested in The Moon is a Harsh Mistress (which I just read last week) and forgo elections entirely in favor of selecting representatives by petition, possibly giving representatives unequal voting power based on the number of their supporters. That way no congressman would represent any minority that opposes his policies, and all minority groups could select alternative representatives.