Peel the ginger and grate it into a medium bowl. Zest in the lemon and juice in half of it. Whisk in ½ tbsp honey and a pinch of salt. Rinse and trim the radishes, discarding the leaves, and slice them as thinly as possible. Add to the gingery marinade. Scrunch together and then set aside.
Peel and finely chop the shallots. Peel and crush the garlic. Trim, peel and finely chop the carrots.
Place a pan over a medium heat. When warm, drizzle in 1 tbsp oil. Add the shallots and carrots and fry for 5 mins till just soft. Add the garlic. Cook for 1 min.
Add the buckwheat into the pan and pour in 400ml boiling water. Cover, bring to the boil and simmer for 15-17 mins till just softened but still with a slight bite to it. Add a splash more water to the pan during cooking if needed.
While the buckwheat simmers, warm a frying pan over a medium heat. When hot, tip in the walnuts. Toast for 2-3 mins till darkened and nutty smelling. Pour in the remaining honey and cook for 1 min till bubbling. Tip onto a plate.
Check the buckwheat is cooked. Drain off any remaining water. Add half of the spinach leaves and fold through till just wilted. Stone and chop the dates and add to the buckwheat along with half the honeyed walnuts.
Taste and season the buckwheat. Add a pinch or two of cayenne pepper (it's spicy, so use as much or as little as you like). Spoon into warm bowls. Top with the pickled radish, drizzling over a little of the gingery marinade, the remaining baby spinach leaves and walnuts. Dollop on the yogurt. Sprinkle over a little more cayenne and serve with wedges of the remaining lemon for squeezing.