In a large bowl, combine the ground beef, finely chopped onion, egg, breadcrumbs, and milk.
Season with salt, black pepper, and nutmeg if using.
Mix everything together until well combined, but be careful not to overmix.
With wet hands, shape the mixture into thick, round patties, about 1/2 to 3/4 inch thick.
Heat the vegetable oil in a large skillet over medium heat.
Add the patties to the skillet, making sure not to overcrowd them.
Cook for about 4-5 minutes on each side, or until they are browned and cooked through (internal temperature should reach 160°F or 71°C).
Remove the patties from the skillet and drain on paper towels.
Enjoy your meal!