RED LENTIL SOUP WITH CRISPY SHALLOTS

3 tbsp olive oil • 400g Waitrose & Partners Shallots, peeled • 1 large carrot, peeled and finely diced • 1 celery stalk, peeled and finely diced • 1 tsp ground turmeric • 1 tsp ground cumin • 1 cinnamon stick • 200g Waitrose & Partners LoveLife Red Split Lentils, well rinsed • 1 litre Cooks’ Ingredients Vegetable Stock • 1 tbsp plain flour • Pinch salt • 1 lime, juice • 4 tbsp natural yogurt