Sift together the brown sugar, flour and salt, then set aside. Beat the egg white until stiff and add to sifted ingredients. Blend in the vanilla extract. Mix all ingredients well with a fork and add the pecans.Coat each pecan completely but not excessively. Place on greased cookie sheet and bake for 20 to 25 minutes at 250-275 degree oven. Allow to cool on cookie sheet Store in airtight container for crispness.