Mix vegan mayo and Provencal mustard until blended. Set aside.
Cucumber
Cut off the ends of cucumber and slice into ¼" slices (or a little bigger).
Mix corn meal, mustard powder, tarragon flakes, and salt in a bowl.
In a separate bowl, pour unsweetened plain almond or soy milk.
In assembly line fashion - dip cucumber into almond or soy milk, then corn meal mixture. Put dredged cucumber on a plate.
Frying: Heat canola oil (you will need about a ¼" or so covering the pan) to 350°. If you don't have a thermometer you can test the oil by dropping a couple of drops of water into oil. If it sizzles, it's ready. Place dredged cucumber pieces into oil, frying in batches. Cook on each side until golden brown and crispy. Baking: Cook cucumber at 450°F for 20 minutes, then flip and cook for another 20 minutes, or until crispy on both sides.