Preheat oven to 200°C, gas mark 6. While oven is heating, remove seeds from chillies, squeeze 2 limes, peel and chop 3 avocados and roughly chop 2 bunches of fresh coriander. Put them all in a blender, and once it's all blended until creamy, season with salt and pepper and pour into a serving dish. Pound 1 bunch of thyme is a pestle and mortar and a glug of olive oil. Brush the tortillas with the flavoured oil. Lay them on baking tray (don't overlap them too much) season with salt & pepper. Bake for 10 mins until golden brown. Leave them to cool and serve with guacamole.