- For comeback dressing, mix all ingredients together in a blender or food processor. (Note: this is a large batch, but it will keep for 2 weeks sealed in the refrigerator.)
- Heat oil in fryer or deep-bottomed stockpot.
- While heating oil, prepare “fries”: pour milk into one bowl and whisk flour with desired seasonings in another.
- Dip portobello strips into flour, then into milk, then back into flour again.
- Drop into hot oil and fry until crispy and golden. Drain on a paper towel-lined plate and season immediately with salt and freshly ground black pepper. Serve with horseradish comeback dressing.