French depression dog

Using a mandoline or a sharp knife, cut your potatoes into 1/4-inch planks and then into 1/4-inch spears of potato.

Add all your potatoes to a large bowl of water for at least one hour. This allows the excess starch to be removed from the potatoes.

After an hour or so, drain the potatoes and dry with paper towels. Attempt to get them as dry as possible. 

Add your oil to a large heavy bottomed pot. You need your oil to be at least 3 inches deep in the pot.

Bring the oil temperature up to 300 degrees F and fry all your potatoes in batches for 3 to 5 minutes. This first stage is to cook the potato all the way through. This isn't going to make your fries turn brown and crispy. That comes in the second fry.

After 3 to 5 minutes, move the par-cooked potatoes to a rack to cool and cook the rest of your potatoes in batches. 

Once your potatoes have been fried once, raise temperature of your oil to 375 F. 

Once again fry your potatoes in batches until they turn golden brown for 1 to 2 minutes. 

Move each batch of fries to a bowl or plate and salt immediately while they are still warm. If it will be a long time before you are ready to sandwich, you can keep the fries warm on a sheet pan in a 200 degree oven.

Dice a quarter of a shallot and 2 or 3 cornichon pickles into a fine dice and add to a bowl or plate for serving.

Grill merguez sausage on a grill or grill pan until it is fully done and registers 160 degrees F (71 C). Merguez links vary in shape, so this may take anywhere from about 10 to 15 minutes on a hot grill. If you have an instant read thermometer it's best to cook the sausages over indirect heat (not directly over the hot coals) with the lid on until the inside of the sausage hits around 150 degrees and then move the sausage to the hot side of the grill to finish off and get some dark color.

Once the sausage is cooked, slice a baguette 3/4ths of the way through, add the sausage and top with a tablespoon of diced shallot, around 2 tablespoons of diced cornichons, 2 or 3 squirts of Dijon mustard and a few spicy peppers. Top everything with the fresh cut fries and serve.