Combine first 4 ingredients.
Add milk and vanilla; beat until smooth.
Add egg, and beat well; stir in butter.
Refrigerate 2 hours.
(This allows flour particles to swell and soften so crepes are light in texture.) Brush bottom of a 6-inch crepe pan or heavy skillet with oil; place over medium heat until just hot, not smoking.
Pour 2 tablespoons batter into pan; quickly tilt pan in all directions so batter covers pan in a thin film.
Cook crepe about 1 minute.
Lift edge of crepe to test for done-ness.
Crepe is ready for flipping when it can be shaken loose from pan.
Flip crepe, and cook about 30 seconds on other side.
(This side is rarely more than spotty brown and is the side on which the filling is placed.) Place crepes on a towel to cool.
Stack between layers of waxed paper to prevent sticking.
Repeat until all batter is used.