Peel the onions, halve and cut into rings. Rinse the leek and cut into rings. Heat the oil in a saucepan and saute the onions and leek until soft. Add the bay leaf. Pour in the broth and wine. Season with salt, pepper and coriander. Simmer for about 10 minutes.
Preheat the grill. Line a baking sheet with parchment paper. Lay the pumpernickel on the sheet and sprinkle with the cheese. Grill until golden brown. Serve the soup with the pumpernickel cheese bread.