Step 1: Sauté the Aromatics
In a large pot or Dutch oven, heat the olive oil over medium heat.
Add the diced onion and sauté for about 3–4 minutes until softened.
Stir in the garlic and cook for another 30 seconds until fragrant.
Step 2: Add the Vegetables
Add the carrots, celery, potatoes, parsnip, and mushrooms. Stir everything well to coat in the oil and aromatics.
Cook for about 5 minutes, allowing the vegetables to slightly soften.
Step 3: Build the Flavor
Stir in the tomato paste, Worcestershire sauce, thyme, rosemary, smoked paprika, salt, and black pepper. Mix well to distribute the flavors.
Pour in the vegetable broth and dark ale (if using).
Add the bay leaf and bring everything to a simmer.
Step 4: Simmer the Stew
Reduce the heat to low and let the stew simmer uncovered for about 30–40 minutes, stirring occasionally.
Once the vegetables are tender, stir in the cooked lentils and green peas.
Step 5: Thicken the Stew
In a small bowl, mix 1 tablespoon of flour or cornstarch with 2 tablespoons of water.
Slowly stir the mixture into the stew, allowing it to thicken. Let it simmer for another 5–7 minutes.
Step 6: Serve and Enjoy!
Remove the bay leaf and adjust seasoning if needed.
Garnish with freshly chopped parsley and serve hot with crusty bread or Irish soda bread.