Potato & Fontina Tart with Smoked Eel: Delicious, Easy Recipe

Ingredients

• 1 x 375g butter puff pastry sheet
• 1 x 600g smoked eel, flesh picked (optional)
• 400g Dutch cream potatoes, peeled and very finely sliced
• 1 brown onion, very finely sliced
• 1/3 cup crème fraîche
• 1 teaspoon caraway seeds, toasted
• 125g fontina, rind removed, sliced
• Salt flakes and freshly ground black pepper, to taste
• 1 egg, lightly beaten
• 25g butter
• 8 sage leaves, torn
• 1/2 cup watercress sprigs