Combine half and half or light cream with flower in a small bowl and set aside.
In a pan, combine dry white wine and shallots, Bring to boiling, reduce heat.
Simmer uncovered for 8 -10 minutes or until the liquid is reduced to about 3 tablespoons, stirring occasionally.
Stir the flour mixture into the wine mixture. Add the white pepper. Cook and stir over medium heat until thickened and bubbly.
Stir in the Dijon mustard.
Cook and stir for one minute more