Put the coriander, caraway and cumin seeds in a dry frying pan and toast for 1 min. Grind in a pestle and mortar. Soak the guajillo chillies in warm water, then drain and remove the seeds (keep the soaking water). Put the spices and the soaked chillies into a blender with the halved red chillies, the garlic, coriander, lemon juice, olive oil and some salt. Add some chipotle paste to taste if you want a smoky flavour. Blend to a thick paste with a little soaking liquid. Put in a sterilised jar and pour over a little extra olive oil. Will keep chilled for up to two weeks.