Hike Distance: 1 mile (1.6 km) loop
Trailhead Distance from Yosemite Entrance: 22 miles (35 km)
Elevation at trailhead: 6,410 feet (1,954 meters)
Elevation Change: 40 feet (12 meters)
The Key: The blue line is the Tioga Road. Follow it west for 12 miles (19 km) and you'll arrive at Yosemite's eastern gate.
The yellow line is Highway 395, or at least the part of it you'll need to get to the Mono Lake South Tufa trail. The green line is highway 120 east (not to be confused with 120 west, the Tioga Road). This road, five miles south of the Tioga Road/395 intersection, is well marked and easy to find. The purple line is the mostly dirt road that takes you the final stretch to the trailhead, and the big green hikers mark the location of the trailhead.
The trail itself isn't marked, but here's a zoomed-in view that shows it.
If you need refreshments, head for the blue balloon, which marks the location of the celebrated Whoa Nellie Deli, or the green balloon, where you'll find the town of Lee Vining.