Mix the sour cream and horseradish in a bowl. Season with salt and pepper to taste.
Toast the bread.
Spread the horseradish sauce on one side of each slice of bread. Layer with spring mix, tomatoes, roast beef seasoned with salt and pepper, and cheese.
In a bowl mix the mayo with chipotle sauce and prep the celery sticks.
Cut the sandwich in half and serve with celery, chipotle mayo, and lemonade.