I preheat the slow cooker right after I finish prepping the vegetables and meat, and I layer my ingredients according to how submerged they need to be from the very start. You may assemble however you like, but I prefer this option for guaranteed very tender meat.

Dice the onion and celery. Wash or peel the potatoes and cut them into 1-inch cubes. Slice the leek and mushrooms. Finely mince the garlic. Keep everything in separate bowls until ready to use.

Cut the beef into 1 inch chunks and season generously with salt and pepper. Coat in about 2 tbsp of flour.

Heat some oil in a stainless steel skillet and sweat the mushrooms, then add the onions until both are soft and the onions are translucent. Set aside.

Add more oil if needed and brown the beef chunks on all sides (usually in 2 batches). You'll want them a little crispy brown on the outside but they don't have to be done on the inside. Put in the (preheated) slow cooker as the first layer.

Add the mushrooms and onions as the second layer, then the potatoes, then the leek and celery as the last layer.

Return the skillet to the burner and set heat to low. Stir fry the garlic until fragrant.

Add the beef broth, oyster and soy sauce, Worcestershire sauce, (brown) sugar, rosemary and thyme. Stir to combine and dissolve the browned bits from the skillet. Then pour into the slow cooker. The sauce will not cover the contents, but that's normal.

Place lid on slow cooker and cook on high for four hours. After 4 hours stir the stew and break the beef into smaller pieces if needed. Taste and adjust the salt or broth amount as needed. Serve hot as is, or over a bowl of rice or pasta.