1kg russet potatoes (about 4 medium), peeled and cubed.
1 yellow onion, thinly sliced
1 tsp neutral vegetable oil
>2 tbsp unsalted butter
2 tsp kosher salt, divided, plus more as needed
500ml low-sodium chicken broth
375ml whole milk
Freshly ground black pepper
SERVING OPTIONS:
Thinly sliced green onions
Shredded cheddar cheese
Sour cream
Crispy bacon strips (reserve fat if using)
Place the 2 tablespoons bacon fat and 2 tablespoons unsalted butter in a heavy bottomed Dutch oven and heat over medium heat until the butter is melted. Add the onion and cook until translucent and lightly browned, 1 to 2 minutes. Add the potatoes, and 1 teaspoon of the kosher salt. Cook, stirring to coat the potatoes in the fat, for 2 to 3 minutes.
Add broth, stir to combine, and bring to a boil. Cover and simmer, reducing the heat as needed, until the potatoes are tender, 15 to 20 minutes. Add whole milk and stir to combine. Turn off the heat.
Using an immersion blender, blitz until smooth. Add the remaining kosher salt, season with black pepper. Stir to combine. Cook over medium-low heat until slightly thickened, 3 to 4 minutes. Taste and season with more kosher salt as needed.
If the consistency is too thick, add 60ml water or chicken broth. If the consistency is too thin, continue to simmer until desired consistency.
Serve the soup topped with the bacon and thinly sliced scallions, shredded cheddar cheese, and sour cream if desired
