Bistro Hamburger au Poivre with Fresh Tomato Leek Sauce

Ingredients
2 lbs ground round
4 shallots, chopped
2 tbsp capers
6tbsp red wine
1 tsp salt
4tbsp Dijon mustard
4 tbsp ground peppercorns

Tomato leek sauce:
$ tbsp butter
2 small leeks
6 plum tomatoes
4 tbsp brandy
2 1/2 tbsp fresh tarragon
6 tbsp cream
1 tsp salt
1/2 tsp black pepper

Mix ground round, shallots, capers, wine and salt in a bowl.
Divide into 6 burgers.  Coat outside of each with Dijon mustard and crushed peppercorns.
Let sit for 30 mins and cook on grill
Melt butter and cook leeks until soft.  Add tomatoes and cook for 3 mins.  Add brandy, tarragon and cream and cook until sauce thickens.