Give your radishes a thorough wash in cold water to remove any grit from the leaves. Halve. Pluck out any wilted or damaged leaves.
Tumble your radishes in a large bowl. Slice your pepper, discarding stem and seeds. Quarter your lettuce. Add it to the bowl. Toast the sesame seeds in a dry frying pan for 2-3 mins till golden. Grind in a pestle and mortar with a drizzle of olive oil to make a rough paste.
Spoon the yogurt into a pretty dish. Dollop the sesame seed paste on top. Use the tip of a knife to swirl it through. Measure your ground cumin into a separate little dish.
This is a gorgeous way to present the salad. When you're ready to eat, simply spoon the dressing into the big bowl of veg. Mix through. Dust a good few pinches of cumin over, to taste (i.e. you might not want the full teaspoon's worth).