Master a Thanksgiving Side Dish: Aroostook Savory Supper

Photograph by Jolyon Helterman

Equipment

• Mandoline, food processor, or very sharp knife for slicing
• Chinois or fine-mesh sieve
• 9-by-13 oven-safe casserole dish or Dutch oven
• Blender

Ingredients

For the onion–salt pork mixture
4 lb. white or Spanish onions, peeled, halved, and very thinly sliced
2 lb. salt pork, finely diced Grapeseed oil
¼ c. grated Gruyère, Comté, or Ascutney Mountain cheese
1 egg yolk
Sherry vinegar or apple cider vinegar, to taste (about 1 tbsp.)
alt and pepper, to taste

For the potatoes
4 lb. waxy potatoes
1 ½ c. rendered pork fat or olive oil
4 sprigs thyme
2 branches rosemary

To serve

• Fresh chives
• Flaky sea salt (such as Maldon)
• 12 to 15 slices lardo, sliced as thinly as possible (optional)

Instructions:

5. Place rendered pork fat or olive oil in a pot and heat gently over medium-low heat until warm (around 100 to 120 degrees Fahrenheit). Add in herbs, remove from heat, and let steep 30 minutes.

4. Peel potatoes and slice on a mandoline (or with a knife) to a 1/16-inch thickness. Pour the herb-infused pork fat or oil over the potatoes and gently toss to coat. Lightly season with salt and pepper, and keep in a warm place.

3. Place onions and salt pork in a high-sided, heavy-bottomed stock pot with a lid. Lightly sprinkle onions with salt, and add in just enough grapeseed oil to lightly coat the onions (about one tablespoon). Cover and cook over medium heat until soft and fully cooked, about 20 to 30 minutes, stirring every few minutes to make sure onions do not stick or color. (Add a few tablespoons of water, if necessary, to avoid sticking.)

4. Purée half of the onion-pork mixture (including half of the liquid in the pot) in a blender until completely smooth. Discard excess liquid that remains in the pot. Pass purée through a chinois or fine-mesh sieve. While still warm, temper the cheese and egg yolk into the purée. Combine the purée with the other half of the onion mixture. Season to taste with vinegar (about one tablespoon). Adjust seasoning with salt and pepper. Chill immediately.

5. In a casserole dish, place down an even layer of potato, then a layer of the onion mixture, and then another layer of potatoes. Build layers until potatoes are about 90 percent of the way up the dish. Bake in a 350-degree oven until fully cooked, about 75 to 90 minutes; cover with foil for the first 40 minutes and then remove. (Check doneness by inserting a cake tester or small paring knife into the dish to test resistance.) Remove casserole from the oven and let rest 20 minutes. To serve: Drape the top of the casserole in lardo (if using). Sprinkle the top with flaky sea salt and chopped chives.