Preheat a Dutch oven over medium heat and add 1 tablespoon of olive oil. Season the pot roast with half of the salt and pepper. Carefully add the pot roast to the Dutch oven and sear on all sides until browned, which should take about 10-12 minutes total. Once browned, transfer it to a plate to rest while you prepare the onions.

Set up a food processor with a thin slicing attachment. Cut your onions in half and peel away their skins. Pass all of the onions through the food processor to get perfectly sliced pieces that will caramelize beautifully.

Add the remaining olive oil to the Dutch oven and tumble in all of your sliced onions. Toss them in hot oil and season with remaining salt and pepper. Cook over medium heat, stirring frequently until they become translucent and limp, which should take about 5 minutes.

Reduce heat to medium-low and cook the onions, stirring occasionally, for about 20 minutes until they take on a light golden color. Be cautious not to burn them—scrape the bottom of the pot often to prevent sticking.

Add garlic along with maple syrup; cook while stirring frequently for an additional 7-8 minutes until softening occurs. Next, sprinkle in flour and stir well before deglazing with apple vinegar followed by pouring in beef broth; mix thoroughly until combined. Return your pot roast back into this flavorful mixture, ensuring it’s covered by liquids, then add rosemary and bay leaf before bringing everything up to a simmer over medium-high heat.