Draw a slightly curved horizontal line for the bottom bun
Add a rounded dome shape above it for the top bun
Draw a wavy line under the top bun for the lettuce
Add a thick oval or rounded rectangle for the patty
Draw a wavy or uneven line under the patty for cheese
Add another wavy line for tomato or onion if desired
Draw a second curved line for the bottom bun edge
Add small sesame seed shapes on the top bun
Outline the burger with darker lines
Color the bun, patty, lettuce, cheese, and toppings