The Greek that is translated in English “(Everyone will be) salted with fire” is translated in Uripiv as “God will test all people with fire, like they test black stones [which are used in cooking]. If a stone is no good, it crumbles to ashes; if it’s good, the fire doesn’t affect it. So also they put salt with food to test its flavour, good or bad.” (Source: Ross McKerras)

See also complete verse (Mark 9:49).