Leek, Potato & Kielbasa Soup

• 2 boiling potatoes (peeled)
• 1/2 kielbasa (diced)
• 1/2 thinly arugula (sliced)
• 1,200 ml chicken stock
• 180 gr leeks only (sliced white rinsed)
• 60 ml cream (heavy)
• 34 gr bell pepper for (finely diced red garnish optional)
• 18 gr butter (unsalted)
• 1 gr fennel seed (lightly crushed)