Shape ground chuck into patties (no more than ¾” thick). Make a depression in the center of each patty with your thumb so the burgers won’t budge.
Heat an outdoor grill or indoor grill pan to high heat. Brush each patty with canola oil and season with salt and pepper. Place patties on the grill and grill burgers until they are fully cooked. Right before the burgers are done top each patty with a slice of cheese and allow it to melt.
Remove patties from grill.
To make avocado relish – in a medium bowl combine avocados, onion, jalapeño pepper, cilantro. Squeeze the juice of 1 lime onto the mixture tossing to coat. Season with salt and pepper.
To assemble burgers- place a patty on the bottom of a hamburger bun. Top with a slice of tomato, lettuce and avocado relish.