You can use some baking soda and dish soap to get burnt food off porcelain.
Take a cloth and put a couple drops of liquid dish soap on the cloth and rub the burnt food on the porcelain in a circular motion to lift the food.
Then sprinkle some baking soda onto the burnt on food on the porcelain and then take a cloth again and gently scrub the burnt on food.
It should come off but if it's more stubborn you may need to soak the porcelain in the sink with hot water and vinegar.
Or put some baking soda in a sink and add some undiluted vinegar to the sink to cover the porcelain and allow it to soak for awhile.
Another option is to soak the porcelain in a sink of hot water and dawn dish soap which usually easily helps lift burnt on food and grease off of any dishes including the porcelain.