Add beef to a 4qt stock pot and cover with water. Bring to a steady simmer over med-high heat. Use a spoon to skim as much foam from the surface as possible. Cook approximately 1 hour or until meat is fork tender.

Add carrots, onion, red pepper and potatoes to the pot. If required, add more water so that it comes almost to the top of the pot. Season with a pinch of kosher salt and bring liquid to a steady simmer.

Using a sharp knife, score an 'X' into the bottom of the tomato. Add tomato to the soup and cook 60 seconds. Remove tomato and run it under cold water. Peel and discard the skin then dice the tomato. Add diced tomato back to the soup and cook vegetables until potatoes are fork tender (approx. 20min).

Add tomato paste to a ladle filled with some of the broth. Stir well to combine before adding the mixture into the soup. Cook 5 min.

Add lovage and lemon juice, stir everything to combine. Taste for seasoning and adjust salt or lemon as required. The soup should be slightly sour.

Serve in individual bowls and garnish with chopped lovage and sliced red onion (optional).