Unlike its relative the onion, leeks have an elegantly tall and slender form - its hue changing from white to dark green as you move along its length. When choosing leek I always look for those that have larger white sections - as it gets greener in colour, the quality of flavour does decrease. This will also guarantee you get the most useable amount of leek from your purchase.
The flavour of leek really comes through when they are simply sauteed in butter until they just soften - as they break down they also develop a lovely creamy texture, something you don't get with onions.
The dish I've made celebrates this - I've made a filling that combines the sweet flavour of sautéed leeks with the subtle earthiness of oyster mushrooms.
To round out the tart, I've studded it with nuggets of Tallegio - that wonderfully aromatic washed rind cheese from Italy.
½ portion Shortcrust pastry
2 leeks, sliced into rounds
2 sage leaves, finely sliced
handful of oyster mushrooms
Taleggio, cut into cubes
⅓ cup cream
⅓ cup milk
Prepare the filling:
Top and tail the leeks (discarding the dark green parts) and slice into rounds - making sure there's no grit in between the layers. Place a good knob of butter in a skillet over a low heat, sprinkle in the finely sliced sage leaves and allow these to release their flavour into the melting butter. Once melted, add in the sliced leeks and gently cook until soft but not coloured. Remove the leeks from the pan and move onto the mushrooms.
For even cooking you need even sizes - keep them bite-sized and cut any larger mushrooms along their length so they keep their shape. Increase the heat under the skillet, add a little more butter and once it is sizzling, add in the mushrooms and quickly saute until golden. Mushrooms need to be cooked at a higher heat so that they sear but not sweat. Once done, remove them and place to one side.
Make the tart base:
Roll out the shortcrust pastry and line a 20cm tart tin. Cover the pastry with baking paper and then pour in beans - blind bake the pastry in a preheated 160°C oven for 15 minutes, remove the paper and place bake in the oven for another 5-10 minutes or until the base starts to look dry.
Assemble the tart:
Scatter the cooked leeks across the bottom of the tart - evenly space out the cooked mushrooms and then add cubes of Taleggio. Briefly whisk the eggs, cream and milk until combined and pour over the filling. I haven't added any extra salt as there is enough in the cheese.
Bake in a preheated 170°C until golden and cooked through - this should take around 20-30 minutes. Let it sit in the tin for a good 5 minutes before un-moulding and serving.