1. Pre-Sliced Sourdough Bread (or your bread of choice)
2. Pre-Sliced Swiss Cheese (or your cheese of choice)
3. Sliced Tomato
4. Grainy Mustard (or mustard/dressing of your choice)
Since it's summer, please note this is the most unbelievably delicious thing to grill! But, if not, use your Forman Grill/panini maker/etc....or whatever device you use to grill inside.
If you are grilling outside, brush one side of the bread lightly with olive oil. Place mustard on inside -- both sides for my taste -- put a couple slices of cheese and then put the tomato slices between. Grill it up! Then when it's nice and toasty and done, gently open it up and throw some slices of arugula inside. Close it back up and YUMMALICIOUS!