Using your hands, mix the beef with the garlic, salt, pepper, and taco seasoning. Shape and flatten the meat into 4 equal round patties, with the centers dipped in; the burgers expand as they are heated, so the thin centers fill out as they cook.
Make guacamole by cutting the avocados in half and removing the pit. Then scoop the avocado flesh out of the skins into a bowl and mash it with a fork. Add the lime juice, and season with salt and pepper to taste. Set aside.
Prepare pico de gallo by dicing and combining the tomatoes, onion, cilantro and lime juice in a bowl. Season with salt and pepper to taste. Set aside.
Preheat grill. Cook burgers 3 to 4 minutes per side. Place a slice of cheese on the the burgers during the last minute of cooking to melt.
Toast whole wheat hamburger buns (we do ours with a little butter in a saute pan on the stovetop like you would a grilled cheese sandwich), place burger on the bottom bun, then pico de gallo on the burger, and smear the guacamole on the top bun. Place the top bun on your burger and enjoy!