Beef stew with beer and gingerbread

Ingredients

• 800 g beef, cut into 2 cm cubes
• 3 slices gingerbread
• 330 ml dark beer, at room temperature
• 1 L beef broth
• 4 carrots, cut into cubes
• 1 onion, cut into thin slices
• 2 cloves garlic, finely chopped
• 1 teaspoon grated ginger
• 2 bay leaves
• 3 cloves
• a few sprigs of thyme
• 2 teaspoons mustard
• 1 tablespoon flour
• 3 tablespoons butter
• salt
• pepper