Cut the leeks to a length of about 18cm (losing length from the green end) and rinse well. Arrange in a single layer in a wide saucepan or frying pan, pour on the boiling water from the kettle, add a pinch of salt, return to the boil, reduce the heat and simmer, covered, for 6–8 minutes.
While the leeks are cooking, roll out the puff pastry on a lightly floured surface to a 25cm square, then carefully transfer the pastry to a baking tray.
Cut a 1-cm strip of pastry from each of the four sides. Dampen the area round the edge of the square with water and trim the pastry strips to fit flat on top of the edges, to resemble a picture frame; press lightly into place.
Drain the leeks and cool under cold running water. Drain again, then wrap in a folded tea towel and press gently with your hands to remove any remaining moisture. Trim the root ends off.
Arrange the leeks inside the pastry case and brush with the mustard. Break the egg into a small bowl and beat lightly, then brush over the border of the tart. Grate the Cheddar cheese and sprinkle it evenly over the top of the leeks.
Position the baking tray on the top shelf of the oven and bake the tart for 15 minutes, or until the pastry is risen and golden and the cheese has melted and is bubbling.
Remove the tray from the oven and cut the tart into quarters with a serrated-edged knife. Serve the portions hot or warm.
NUTRIENTS PER SERVING:
good source of vitamins A, B group, C, E and folate.
When you shop for this recipe, buy the well-trimmed leeks that are now available in many supermarkets. This will cut down on your preparation time.
This dish makes a perfect spring and summer evening meal with a green side salad. I steamed the leeks instead of boiling them to retain more of their flavour and used a really sharp cheddar; the mustard adds just the right amount of tanginess. It's also quick and easy to make. Recommended, especially if you're running short on prep time. - 01 Sep 2015