Pick the leaves off the mint and parsley and put them to one side. Pour all the rice and barley into a deep saucepan with the bulb of garlic and the herb stalks and cover with cold water. Bring to the boil and simmer gently for 20 minutes. If using farro cook for 30 minutes before adding the rice, as it needs around 50 minutes in total. Check the grains are soft to the bite then cook for 1 minute more. Drain through a sieve, saving the cooking water.
Keep the grains in the sieve and place it over the saucepan containing the cooking water. Cover with a lid and place back on the heat so the grains steam for about 10 minutes. Turn off the heat and tip the grains into a bowl to cool down.
Pick out and discard the herb stalks, then pick out the garlic bulb and squeeze all the cloves so the garlic inside goes into a bowl. Lightly mash the garlic with the back of a fork. Chop the herb leaves and stir these into the garlic. Season well with salt, pepper, plenty of extra virgin olive oil and the lemon juice. Stir this dressing through the cooled grains. Give it a taste and adjust the seasoning if you need to.
Heat a splash of olive oil in a frying pan and add the fennel and cumin seeds and the oats. Stir and fry for a few minutes until the seeds start smelling fantastic and the oats are lightly toasted.
Spoon the grain mixture into a serving dish, stirring through half of the spiced, toasted oats and sprinkling the rest over the top. Drizzle with a little more olive oil, scatter some chopped parsley over the top and serve.