If using pearl onions, bring a small saucepan of water to a boil. Add the onions for about 30 seconds, drain carefully, and remove their skins. Set aside.
Preheat the oven to 350°F (175°C).
Place a large, deep oven-safe skillet or Dutch oven over medium heat. Add the turkey bacon and cook until lightly browned.
Transfer the turkey bacon to a plate and set aside. Leave about 1 tablespoon of rendered fat in the skillet. If necessary, add a small amount of olive oil.
Add the thinly sliced sirloin. Sprinkle with the beef seasoning and sauté until browned. Transfer the beef to a plate.
Add the diced celery to the skillet and cook for several minutes until it begins to soften.
Add the minced garlic and cook for about 30 seconds, stirring constantly.
Pour in the non-alcoholic stout-style beverage or broth and halal-certified Worcestershire-style sauce. Scrape the bottom of the skillet to loosen the flavorful browned bits.
Bring the liquid to a gentle simmer.
Return the browned beef to the skillet. Stir in the broth, tomato paste, bay leaf, and dried thyme.
Add the potatoes, carrots, and prepared pearl onions. Stir gently and bring the mixture back to a simmer.
Combine the cornstarch and cold water in a small bowl until completely smooth.
Slowly stir the slurry into the simmering stew.
Add the sliced mushrooms and simmer uncovered for approximately 10 minutes, or until the mushrooms soften and the gravy begins to thicken.
Return the cooked turkey bacon to the pan. Reduce the heat to low while preparing the dumplings.
For the dumplings, combine the self-rising flour and garlic powder in a medium bowl.
Cut in the vegetable shortening until the mixture resembles coarse crumbs or small peas.
Fold in the shredded Cheddar cheese.
Pour in the milk and gently stir until the dry ingredients are just moistened. Avoid overworking the dough.
Use a small cookie scoop or spoon to portion the dumpling dough over the surface of the Irish Stew with Cheddar Dumplings. Leave space between the dumplings because they'll expand while baking.
Transfer the uncovered skillet to the preheated oven.
Bake for approximately 30–40 minutes, or until the dumplings are puffed, lightly browned, and cooked through.
Remove the bay leaf before serving.
Garnish with sliced green onions and chopped fresh parsley if desired. Serve hot.