Mornay onion tart


Mornay onion tart
In a shortcrust pastry base, a rather thick onion tart, where onions and lardons are deliciously bound with a Mornay sauce.
29 K 4.9/5 (28 reviews)
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Last modified on: June 23th 2024
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For 6 people, you will need:

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Times for this recipe
Preparation: 1 hour 3 min.
Cooking: 1 hour 15 min.
All in all: 2 hours 15 min.
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Step by step recipe


Stage 1 - ⌛ 20 min.
Mornay onion tart : Stage 1
Roll out 300 g shortcrust pastry (pâte brisée) then line a 22 cm (9-inch) diameter high-sided baking tin, which you will have placed on a sheet of baking paper in a baking tray.

Leave any excess dough around the edges, then place in the fridge to set aside.

Stage 2 - ⌛ 10 min.
Mornay onion tart : Stage 2
Prepare and slice 1 kg onion (a mandolin is ideal for this).
This may seem like a lot, but don't worry, they'll reduce when cooked.

Stage 3 - ⌛ 3 min.
Mornay onion tart : Stage 3
In a large saucepan over medium heat, melt 50 g butter, and when hot, add the onions.

Season with salt and stir well.

Cover for the first 5 minutes.

Stage 4 - ⌛ 10 min.
Mornay onion tart : Stage 4
Leave to cook until the onions are tender, checking the salt seasoning as cooked onions tend to be a little sweet.

Stage 5 - ⌛ 5 min.
Mornay onion tart : Stage 5
Your onions should be fairly dry, with little or no cooking juices.
If this isn't the case, because they've given off a lot of water during cooking, drain them in a fine sieve.

Set aside.

Stage 6 - ⌛ 3 min.
Mornay onion tart : Stage 6
Preheat oven to 200°C (390°F).

Cut 150 g smoked pork belly (or thick cut streaky bacon) into small pieces.

Stage 7 - ⌛ 8 min.
Mornay onion tart : Stage 7
Toast them, without adding fat, in a small frying pan over medium heat.

Stage 8 - ⌛ 1 min.
Mornay onion tart : Stage 8
When toasted to your liking, add 4 tablespoons vinegar, and stir until evaporated.

Stage 9 - ⌛ 2 min.
Mornay onion tart : Stage 9
It's not essential, but I recommend adding 2 or 3 spoonfuls of already-cooked onions to the pan at the end of cooking, then stirring well to capture all the flavor of the grilled bacon.

Stage 10 - ⌛ 2 min.
Mornay onion tart : Stage 10
Pour the lardons + onions into the remaining onions and mix well.

Stage 11 - ⌛ 2 min.
Mornay onion tart : Stage 11
Add 300 g mornay sauce and mix well.

Stage 12 - ⌛ 20 min.
Mornay onion tart : Stage 12
Take the pastry mould out of the fridge, cut the excess pastry around the edges of the mould, place a sheet of baking paper on the bottom and fill with ceramic balls (or similar).

Bake at 200°C (390°F) for 20 minutes.

Stage 13 - ⌛ 5 min.
Mornay onion tart : Stage 13
In the meantime, you can roll out the pastry scraps into small strips to decorate the tart.

Stage 14 - ⌛ 1 min.
Mornay onion tart : Stage 14
After 20 minutes, remove the baking tray from the oven...

Stage 15 - ⌛ 5 min.
Mornay onion tart : Stage 15
... and remove paper and beads.

Stage 16 - ⌛ 2 min.
Mornay onion tart : Stage 16
Fill the tart with the onion-lardon-Mornay mixture.

Stage 17 - ⌛ 2 min.
Mornay onion tart : Stage 17
If you have made some, place the pastry strips on top.

Stage 18 - ⌛ 3 min.
Mornay onion tart : Stage 18
Sprinkle with a little grated cheese.

Stage 19 - ⌛ 30 min.
Mornay onion tart : Stage 19
Bake for a further 30 minutes.

Stage 20
Mornay onion tart : Stage 20
Enjoy warm or hot, on its own or with a small green salad.
Remarks
If you find your onions a little too soft at the end of cooking, you can add a good glass of dry white wine.

If you don't have a Mornay sauce, use a Béchamel sauce to which you can add grated cheese to taste.

You'll notice that in this recipe, the onions are cooked without coloring, but if you prefer, you can caramelize them. In this case, increase the weight of onions to 1.5 kg, as they will reduce even more.
Keeping: 1 or 2 days in the fridge, protected by cling film.
Source: Home made.
Nutritional information
Proteins (gr)Carbohydrates (gr)Fats (gr)Energy value (in k-calories)Energy value (in k-joules)
Whole recipe360 RDI=140 %1,490 RDI=140 %1,280 RDI=200 %3,420 RDI=170 %14,320 RDI: 170 %
Per 100 g20 RDI=7 %80 RDI=7 %70 RDI=10 %180 RDI=9 %760 RDI: 9 %
Per person60 RDI=20 %250 RDI=20 %210 RDI=30 %570 RDI=30 %2,390 RDI: 30 %
The % figures are calculated in relation to the Recommended Dietary Intake , or RDI of 2,000 k-calories (or 8,400 k-joules) per day for a woman
Possible allergens in this recipe: Gluten, milk, egg, Sulfites
How much will it cost?
  • For 6 people : 5.40 €
  • Per person : 0.90 €

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Note: Be careful, these prices are only an estimate, you can consult the table of prices by ingredients used for this estimate.
This recipe uses (among others)
Mornay Sauce
Mornay Sauce

You can get more informations, or check-out other recipes which use it, for example: Spinach Mornay, Small green vegetables in Mornay sauce, Eggs Florentine, Manou's zucchinis garnished, ... See them all 4

Shortcrust pastry (pâte brisée)
Shortcrust pastry (pâte brisée)

You can get more informations, or check-out other recipes which use it, for example: Tarte à l'coloche, Black sesame flan, Potato and cheese pie, Deep leek and potato quiche, Potimarron and Parmesan tart, ... See them all 16

Smoked pork belly (or thick cut streaky bacon)
Smoked pork belly (or thick cut streaky bacon)

Like these other recipes: Warm lentil salad, Dandelion salad, New Zealand pies, Boeuf (beef) bourguignon, Soup Cornouaillaise, ... See them all 7

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