For two burgers:

About 2/3 pound lean ground beef (preferable Kobe)

Salt and pepper

2 tablespoons horseradish

2 tablespoons mayonnaise

4 slices sharp Cheddar cheese

4 hand-cut slices rustic, crusty Italian-style bread

Form two oval-shaped patties of the beef (to fit the bread).  Warm a little olive oil in a medium skillet and fry burgers, turning once and flattening with the back of a metal spatula.

Meanwhile, in a small dish, combine the horseradish and the mayonnaise.

When burgers are done, spoon horseradish sauce on top and cover with cheese.  Cover and cook another minute until cheese melts.  Serve on bread slices.  Note:  I don't think this needs another thing, it's so packed with flavor.  But if youmust use ketchup...