many different ingredients can be incorporated with lentils to form a patty, here are several i used...

1 cup cooked lentils
1/4 large onion, small dice
2 garlic cloves, minced
1 long sweet red pepper, small dice
1/4 cup rolled oats
1/8 cup spelt flour (whole wheat would work too)
1 egg white
about 2 tbsp prepared pesto, check out my recipe
salt and pepper
olive oil
saute onion and red pepper in about 2 tbsp olive oil for about 5 minutes on medium heat, then add garlic and cook another minute or is important to add the garlic last so it doesn't burn!  let veggies cool.  meanwhile, combine lentils, oats, flour, egg white, pesto, salt and pepper(i'd say about 1/4 tsp each), and any other spices you feel would be good....i added a little cumin and dry mustard.  add cooled veggies and thoroughly combine.  form into patties, i made 3, then refrigerate to harden them up a bit. 

spray a large pre-heated(medium-high) non-stick skillet with cooking spray and cook patties for about 5-6 minutes each side.  a nice golden-brown crust should be formed.  enjoy with a whole grain and/or your favorite roasted vegetables.  i served it with my "Beautiful Brussels"  check out my recipe

i liked the texture a lot, however, i think i put in too much pesto.  i probably used about 3 tbsp instead of 2 and it was a little challenging forming the patties because the "batter" was a little loose.  but once they were in the hot pan and the crust began to form, they held together pretty well.  i still think 2 tbsp pesto is enough.  and, you can absolutely do these without pesto!  you could add some cheese instead....crumbled feta may be good or even a shredded sharp cheddar.  

what type of veggie burgers have you made???