Sear meat: Heat a large pot or Dutch oven over medium-high heat. Add the oil. When the oil is hot, add half of the stew meat. Arrange in a single layer and do not stir. Allow the meat to sit, undisturbed, until golden to dark brown on the bottom. This will take about 5 minutes. You do not want to cook the meat all the way through; you just want to give one side a good sear. When done, transfer the seared meat to a bowl and repeat with the second batch.
Sauté onions: Add the chopped onions and bacon to the pot. Give them a good stir to coat them in the residual oil, and then let them sit, undisturbed, to let them brown just a bit. After 5-10 minutes, add the garlic and tomato paste. Stir and allow to cook for 1-2 minutes.
Make roux: Sprinkle the flour over the mixture and stir to coat. Allow the flour to cook for several minutes while stirring to prevent burning. The mixture should start to stick to the bottom of the pan.
Deglaze: Add the stout to the mixture and stir with a flat bottom spoon to release anything that may have stuck to the bottom of the pot. A rich, thick gravy will form.
Braise meat: Add the beef broth, thyme, bay leaves, and seared stew meat (along with any liquid in the bowl) to the pot. Stir well to combine. Allow the mixture to come to a gentle simmer, then reduce heat to the lowest amount needed to maintain a gentle simmer. Cover the pot loosely and simmer for one hour.
Cook potatoes and carrots: After the stew has cooked for at least an hour, stir in the prepared potatoes and carrots. Mix in the salt. Continue cooking with a gentle simmer, uncovered this time, for another hour. As the liquid evaporates with the lid off, the stew will slightly thicken.
Season and serve: Taste the stew and add freshly ground pepper and additional salt, if needed. Remove the thyme stem and bay leaves prior to serving. Tastes great with Irish soda bread!