This sandwich is easy to assemble at home or on board and each of your guests can slice off the amount they want. It may be safest to consider it a “knife and fork” sandwich and offer the necessary cutlery, it can get a little messy.
Bake the circle in the 450 degree oven for 25 minutes, the circle should puff up about 3x and be nicely browned.
Can be wrapped in plastic wrap and stored for up to 24 hours.
Roughly, here is the formula: 2 parts olive oil, 1 part tarragon vinegar, a large dollop of Dijon mustard and lots of chopped garlic. Put all of the ingredients in a screw-top jar and shake it up until the mix becomes beautifully emulsified.
Sprinkle on the capers and chopped parsley.