Place the flax seeds and water in a blender or food processor and pulse a few times.
The flax will help bind the mixture. Add the beets, beans, basil, garlic, salt and pepper and pulse until the mixture is combined and all the ingredients are coarsely to finely chopped.
Remove mixture and form into patties. 
heat a frying pan over medium high heat and coat with cooking spray.
cook patties for 5 minutes, then gently flip over and top with cheese if using.
Cook another 5 minutes. 
Meanwhile, cut rolls in half crosswise and toast under a broiler or in a toaster.
Place patties on bottom buns and top with tomato, onion, pickles, avocado and greens.
Drizzle dressing over the greens or on the cut side of the top bun.