How to Make the Ultimate Pastrami Croque Monsieur - The Secrets of French Cuisine

For the mornay sauce

In a saucepan, place the milk with the onion, shallots, nutmeg, and thyme.

Bring it to a simmer and let it steep for 10-15 min.

Meanwhile, make a roux by whisking the flour and butter in a small saucepan for 2-3 min or until the flour is cooked off.

Strain the milk and discard the aromatics.
 

Slowly whisk the milk into the roux. Cook the béchamel until obtaining the desired consistency.

Season with salt and pepper. Add the cheese and lemon zest.

Place the mornay in a container, place a piece of plastic wrap over the sauce to prevent from creating a skin and set aside.

For the pickled shallots

Place all the ingredients except the shallots in a saucepan and bring it to a simmer.  

Let it steep for 5 minutes
 

Slice the shallots thin and split the rings.
 

Pour over the pickling liquid, cool down and reserve.

Duck fat fries

Peel and cut the potatoes to the desired size.

Place the fries in a large pot with salted cold water. Bring it to a boil then strain. Place them in a tray over a towel or absorbing paper and let it cool down at room temperature.

Bring the duck fat and canola oil to 250F and cook the potatoes for 4 minutes. Take them off and place on top of the same tray with a towel. Cool down at room temperature.

Bring the duck fat oil to 350F and cook the fries until golden brown and crispy, about 3-4 min.

Place in a bowl with a paper towel and season right away.

Croque monsieur

Start by buttering the inside of the bread, place the pastrami on one side and top up with some pickled shallots and Gruyère.

Spread mornay on the other side of the bread and on top of the cheese. Close the sandwiches and spread mayo on the outside layers of the bread.

In a frying pan, place the butter until foaming and add the sandwiches. Cook until golden brown and flip them on the other side.

Place the pan in a 350F oven for 5 min.

Slice the sandwiches in half and serve with the duck fat fries.