Responsa על חולין 221:24

You have rendered unfit for eating purposes meat that was not rinsed before it was salted and cooked. Your decision in this case, however, is not correct since the talmudic law requiring that meat be rinsed before salting is a requirement previous to the act (לכתחלה) which law does not render unfit for eating purposes meat that was already salted without a previous rinsing (בדיעבד).
SOURCES: Cr. 55; Pr. 992; L. 337; Rashba I, 870. Cf. Wertheimer 3; Sefer Haparnes 30.