Whip evaporated milk until light. Add orange juice and pulp. Stir in sugar. Freeze in a leak-proof plastic container.
Check after about 40 minutes. When the mixture begins to become slushy, shake or stir to mix well and break up crystals; stir up the orange at the bottom of the container if it has settled.
After stirring, return mixture to the freezer and stir again every 30 minutes or so, until completely frozen and ready to serve.
Variation: May be used to fill popsicle molds (no stirring). Insert a stick into the mold when the mixture has nearly frozen and return to freezer.
