Fennel Soup with Toasted Seed Oil and Horseradish

Ingredients

• 1 onion, finely chopped
• 40 gm piece of prosciutto (see note)
• 12 garlic cloves, peeled
• 120 ml olive oil
• 1 1/2 litres chicken or vegetable stock (6 cups)
• 6 fennel bulbs (1.5kg), diced, and 1 cup fronds finely chopped, to serve
• 300 gm sour cream
• Finely grated horseradish, to serve
• Toasted fennel seed oil
• 120 ml grapeseed oil or light olive oil
• 1 tbsp fennel seeds, crushed (between coarse and fine)