Combine flour, salt, pepper and thyme; roll trout in seasoned flour.
Cook trout in margarine in skillet over low heat until browned on both sides.
Place trout on heated platter; keep hot.
Brown butter in saucepan.
Add mushrooms; saute for 5 minutes.
Add lemon juice, parsley, chives and salt.
Simmer, stirring constantly, until heated through; pour over trout.
Garnish with lemon slices dusted with paprika.