On the toasted french bread lightly sprinkle white wine to moisten. Then spread with dijon mustard and sliced tarragon. Place your tomato on top followed by sliced guyere cheese. Stick under the broiler until the cheese is melted.
Enjoy!
Recipe by a sonoma garden at http://www.asonomagarden.com/2014/10/02/open-faced-tomato-guyere-sandwich/