To make the filling, cut the mushrooms and leeks into small slices.
Heat oil in a frying pan and when hot, add a knob of butter and the mushrooms and leeks. Cook the leeks and mushrooms till soft and a light brown.
Add the flour and mix through, cooking for a couple of minutes.
Then add a third of the milk and mix through, gradually adding the final two thirds of the milk as the mixture thickens.
Add salt and pepper to season and leave to cool slightly.
To make the pancakes, in a bowl whisk the flour, eggs and milk until light and fluffy. Heat some oil in a frying pan, then pour in a thin layer of the batter to make a thin, light pancake.
Fry the batter for few minutes or until the bottom of the pancake is golden brown, then flip the pancake to cook the other side.
Repeat until you have 12 pancakes, leaving the pancakes to stand and cool slightly.
Dice the onion and gently fry over a low heat in oil until transparent.
Add the garlic and fry for a further two minutes.
Add the tinned tomatoes and turn up the heat until the mixture starts to simmer.
Add the tomato puree, bouillion, oregano, sugar and seasoning to taste.
Turn the heat down low and simmer for 10 to 15mins.
Turn heat off and allow the mixture to cool.
Taste to check for further seasoning, and mix with a hand blender to make the mixture smooth.
Preheat the oven to 200°C / 400°F / gas mark 6.
Assemble the pancakes by rolling each pancake filled with the leek and mushroom mixture, ensuring each pancake is folded at the bottom. Line the pancakes in a large dish and top with the tomato paste.
