Toast the bun. I keep my Ezekiel burger buns in the freezer and I just toast them when I need them.
Heat the falafel
There are several different ways to heat your falafel but my favorite is the microwave: wrap the frozen burger in a paper towel, place on a microwave save dish and heat on high for 60 - 70 seconds.
Add the falafel to the bun and garnish with some cilantro, tomato or cucumber.
Notes
The garnish could be anything. I have used hummus and I have added some of my chopped veggies that I had made the day before for a salad - be creative and add what you like and that tastes good to you.