Artichoke Soup

Ingredients

• 4 large artichokes, trimmed to hearts
• 1 tbsp olive oil
• 1 leek trimmed, cut in half lengthwise,
• thoroughly cleaned and thinly
• sliced (about 1 1/2 cups)
• 1 large potato, peeled and diced
• 1 celery stalk, chopped
• 1 bay leaf
• 4 cups reduced-sodium beef stock
• 2 tbsp fresh lemon juice
• 1 egg yolk
• salt & freshly ground black pepper to taste