Tennessee Cream Gravy

4 tablespoons butter
4 tablespoons flour
1 teaspoon black pepper
2 teaspoons salt
1 cup warm water
13 ounces evaporated milk

Heat fat moderately; stir in flour.
Mixture should be thin - not cakey or oily.
Cook until medium brown, stirring constantly.
Add pepper and salt.
Working very quickly, add warm water; stir thoroughly; let bubble.
Add evaporated milk.
Lower heat and cook to desired thickness, stirring almost constantly.
If necessary to thin at this point, add warm water.