How to change parts of an objects color through scripting?

I am creating a semi-realistic burger cooking style game and I wish to be able to change half of my burger patty's object (one shape, basically a hockey puck) color from pink to a cooked color as it is on the grill. I have done my research on different ways like vertex shaders or projectors, but I was wondering if anyone had advice on a specific technique that would be best for this problem. Thank you!