Heat the oil in a pan, stir in the rice, then pour in the boiling water or stock. Add the salt, stir once and allow it to come back to the boil. Cover, then reduce the heat to give a bare simmer. Cook gently for 40-50 minutes or until all the liquid has been absorbed and the rice is just tender.
Next chop up the spinach leaves and spring onions very finely, and fork into the rice along with the herbs and grated lemon rind. Cover the pan with a folded cloth and leave aside for 10 minutes.
Make the dressing by crushing the salt, peppercorns and garlic together with a pestle and mortar. Add the mustard, vinegar and olive oil, the shake the whole lot together in a screw-top jar.
Tip the salad ingredients into a bowl, pour the dressing all over and fluff it with a skewer. Serve the salad warm or cold. .