MÜHLE is German for Mill and Mittel is also a German word with many meanings.
From Paul Cannon, "I believe this can be read as ‘KÖNIGSBERGER SCHÄLMÜHLE’ around ‘S. WINTER’ ie Konigsberg Hulling Mill. For another of S Winter’s (but different) seals see Euro-Plombs. This uses the same grading style and the word ‘POL’. According to the link Winter’s mill specialised in hulling peas, pea flour, oats and French barley. After World War II Konigsberg passed to Russian control and was renamed Kaliningrad."