Add beef to a medium-sized bowl. Season beef with salt and pepper. Add 1 tablespoon of soy sauce and the minced garlic, stir to combine.
Heat large saute pan over medium-high heat, add 1 tablespoon vegetable oil and 1 teaspoon sesame oil.
Once the oil is very hot, add beef mixture in one single layer. Sear meat on one side for 2 minutes, flip and cook another 2 minutes on other sides. Beef will not be fully cooked.
Add potatoes, onions, carrots and seared beef to a slow cooker.
Add beef stock, oyster sauce and ginger slices. Make sure the meat and vegetables are submerged in the stock. Cover and cook for 3 to 4 hours on High, or 7 to 8 hours on Low.
In a small bowl make the cornstarch slurry by combining ¼ cup of cornstarch and ¼ cup of cold water.
Add it to the slow cooker and stir. Set slow cooker on high and cook another 30 minutes, until sauce is thickened.
Heat large pot over medium-high heat, add 1 tablespoon vegetable oil and 1 teaspoon sesame oil. Add beef mixture and ginger to the pot, sear meat on all sides. Reduce the heat to medium.
Add 1 tablespoon of oyster sauce to the pan and stir. Add onions to the pot, stir and cook for two minutes. Add the potatoes and carrots to the pot. Add 3 cups of beef stock, covering the meat and vegetables.
Bring a pot to boil then gently simmer until potatoes and carrots are fork tender, about 30 to 45 minutes.
In a small bowl make the cornstarch slurry by combining 1/4 cup cornstarch and 1/4 cup cold water. Increase the heat to medium, allowing the stew to boil gently. Gradually add the slurry, mix the stew and allow the stew to cook and thicken for a few minutes. For a thinner sauce, start by adding half of the slurry, then additional slurry until you reach your desired consistency.