• Soak the chickpeas in a large pot of water overnight or for up to 6 hours. Drain once soaked and return to the pot, covered comfortably with more water.
• Set the pot over a high heat on the stove and bring to the boil, removing any scum that rises to the surface. Add the bicarbonate of soda – the chickpeas will bubble and froth almost instantly.
• Skim the froth from the surface, lower the heat to a gentle simmer, add the onion, carrot and whole garlic cloves, and cook, skimming the surface scum periodically, until the chickpeas have completely softened and are all but falling apart. This can take up to 2 hours, sometimes longer. Top up the water if needs be. You need the chickpeas to be completely soft and to fall apart easily with the lightest of pressure.
• Once cooked, turn off the heat, season with ½ tbsp salt and leave in the water for 30 minutes or so.
• Drain the chickpeas, reserving the cooking liquor. Pick out the carrot and onion; transfer all but a few tablespoons of chickpeas (for garnish) to a food processor. Add the tahini, lemon juice, grated garlic and cumin and blitz, ladling the cooking liquor back into the processor gradually until the desired consistency is achieved. The hummus must be as smooth as your food processor allows. It will thicken considerably once cooled and refrigerated. Taste for seasoning – it may need some salt or lemon juice.
• Transfer the hummus to a serving plate and serve topped with tahini sauce; the reserved chickpeas and seasoning. Dot paprika and za’atar around the plate. Sprinkle with parsley and finish with a generous drizzle of the best olive oil you can buy. Serve with warmed pita, or bread of any description.

For the tahina sauce (makes about 220g):

• Pour the tahini paste into a bowl and add the lemon juice and garlic (if using). Gradually whisk in the iced water, gradually, as you pour.
• The tahini will thicken to a very coarse paste, but will loosen to form a thick sauce the consistency of honey as you add more iced water. Season with salt to taste.