Half the bread in your sandwich.
Bread and carbohydrates can be the enemy of weight loss and maintenance. Most bread is low in fiber will not keep you full long and many of us who are trying to lose or maintain our weight struggle with the number of carbohydrates we eat. If you put you sandwich on one piece of bread of 2-half pieces of bread, you will reduce your calories. Double up on the veggies, and it will keep you full longer.
Bottom line: Halving the bread and making it an open sandwich or burger will reduce your calories. Use the veggies to increase the size of the sandwich and keep you feeling full longer.