FIG. 1: is a side perspective view of a sanitary mixing valve, especially the visible part of a built-in mixing valve, showing my new design; FIG. 2: is a front elevation view thereof; FIG. 3: is a side elevation view thereof, the opposite side being a mirror image; FIG. 4: is a top plan view thereof; FIG. 5: is a bottom plan view thereof; and, FIG. 6: is a rear elevation view thereof.