I use between 75% and 90% lean ground beef when making burgers, to eliminate some of the fat content. If you wish to lessen the fat content of the finished burger even more, it can be broiled or grilled. When the girls were growing up, we often used a George Foreman grill placed on the counter for this purpose, with tasty results.
Many people like to spice up there burgers; add a new taste every so often. Just for something different. I love mine with shredded cabbage, shredded zucchini, sweet or bread and butter pickles and tomato slices, along with a slice of mozzarella or provolone cheese.
Here are a couple of other topping options.
Paleo barbecue sauce, cheese, and thin chicken strips.
Pineapple, Swiss cheese, and ham.
And a couple of filling options.
Drained, crushed pineapple and diced chicken, mixed with some Paleo sweet and sour sauce.
Chopped bacon and cheddar cheese.
(Update January 2017: Given that I’m mainly eating Paleo now, I’m not using hamburger buns. That’s right. I’ve gone bunless. I do want to experiment with making Paleo hamburger buns at some point, but haven’t had the chance.