Thomasina's Beetroot & Fennel Seed Soup - Veg Power

Ingredients

• 6 medium beetroots
• 3-4 floury potatoes (about 500g)
• 4 tbsp olive oil
• 2 small onions, finely chopped
• 1 tsp fennel seeds
• a few pinches of chilli flakes (optional)
• 2 fat garlic cloves, finely chopped
• 1.5 litres chicken, beef or vegetable stock
• large thumb-sized piece of fresh ginger, peeled
• 250ml creme fraiche
• finely grated zest of 1 lime and juice of 1/2 lime