Prepare the potatoes first so they can cook while you work on the beef. Peel the russet potatoes and cut them into evenly sized chunks, about 1 1/2 inches each, so they cook at the same rate.

Place the potato chunks in a large pot and cover them with cold water by about 1 inch. Add a pinch of salt if desired, then set the pot over medium-high heat and bring to a gentle boil.

Reduce the heat to maintain a steady simmer and cook the potatoes for 15 to 20 minutes, or until they are very tender when pierced with a fork and almost starting to break apart at the edges.

While the potatoes are simmering, start the beef. Pat the beef stew meat dry with paper towels, then season it evenly with the kosher salt and black pepper.

Heat the olive oil in a large, heavy-bottomed pot or Dutch oven over medium-high heat. When the oil is hot and shimmering, add the seasoned beef in a single layer, working in batches if necessary to avoid crowding the pan.

Sear the beef on each side for 3 to 4 minutes, until well browned. Transfer browned pieces to a plate and continue with the remaining beef until all of it has been seared.

Reduce the heat to medium. In the same pot, add the chopped yellow onion. Cook, stirring often, for 4 to 5 minutes, until the onion is softened and lightly golden, scraping up any browned bits from the bottom of the pot.

Stir in the minced garlic and cook for about 30 seconds, just until fragrant, being careful not to let it burn.

Sprinkle the all-purpose flour over the onion and garlic mixture. Stir constantly for 1 to 2 minutes to coat the vegetables and cook off the raw flour taste, forming a light roux on the bottom of the pot.

Gradually pour in the beef broth while stirring, making sure to whisk or stir well to avoid lumps. Continue stirring until the mixture is smooth and slightly thickened.

Add the Worcestershire sauce, dried thyme, and dried oregano to the pot, stirring to combine them evenly into the broth mixture.

Return the seared beef and any accumulated juices from the plate back into the pot. Stir to coat the beef in the flavorful liquid.

Bring the mixture to a gentle boil, then reduce the heat to low. Cover the pot with a lid and let the beef simmer for 45 to 60 minutes, stirring occasionally, until the beef is very tender.

While the beef simmers, check the potatoes. When they are fork-tender, drain them well in a colander and return them to the hot pot. Let them sit for a minute or two so some of the excess moisture can evaporate.

Add the unsalted butter for the mashed potatoes to the hot potatoes. Begin mashing with a potato masher or pressing through a ricer until mostly smooth.

Pour in the warmed whole milk a little at a time, mashing and stirring as you go, until the potatoes reach your desired creamy consistency.

Season the mashed potatoes with the kosher salt for the potatoes and the black pepper for the potatoes. Taste and adjust the seasoning if needed, then cover the pot to keep them warm over very low heat or off the burner.

When the beef is tender, remove the lid from the pot and bring the mixture back to a gentle simmer. Add the wide egg noodles directly into the pot, stirring them into the broth and beef.

Cook the egg noodles in the simmering liquid for 8 to 10 minutes, stirring occasionally, until they are tender but still hold their shape and much of the liquid has been absorbed into a rich gravy.

Turn off the heat and stir in the sour cream and the unsalted butter for finishing the beef and noodles. Mix until the sour cream and butter are fully incorporated into the sauce, creating a silky texture.

Stir in most of the chopped fresh parsley, reserving a little for garnish. Taste the beef and noodles and adjust the seasoning with a bit more salt or pepper if desired.

To serve, spoon a generous mound of the warm mashed potatoes onto each plate or into shallow bowls, spreading them slightly to form a bed.

Ladle the hot beef and noodles over the mashed potatoes, making sure each serving includes plenty of tender beef, noodles, and gravy. Sprinkle with the remaining chopped fresh parsley and serve immediately.