I like this salad cold but you could certainly rinse the soba noodles under hot water instead of cold water, toss it all together and serve hot. A quick logistics note: there are pepitas in both the salad and the pesto, so plan to purchase and use 1 1/2 cups total. Next time I make this, I’m going to top each serving with a bit of lemon zest, and maybe even fold chopped parsley into the salad itself. Red chile flakes would be nice, too.
Cook the soba noodles in a medium pot of boiling salted water for 4 minutes. Drain then rinse thoroughly under cold water. Drain again and pat dry.
Toast the seeds: Preheat the oven to 350 F. Lay all of the pepitas (1 1/2 cups) in an even layer on one side of a rimmed baking sheet and sesame seeds on the other side. Toast for about 5 minutes, or until slightly fragrant — the sesame seeds should become more golden than white. Remove from the oven and allow to cool.
Make the pesto: Pulse 3/4 cup toasted and cooled pepitas in a food processor until smooth. Add parsley, garlic, chives, oil and Parmesan and process until smooth. Fold in lemon zest and season with salt and pepper.
Assemble: In a large bowl, toss together the soba noodles with the radishes, green onion, cucumber, toasted seeds (I reserve about a tablespoon of each to sprinkle on top) and ¾ cup – 1 cup parsley pesto. Taste and season with salt and pepper. Fold in the ricotta salata at the end. Divide into serving bowls and sprinkle with some the reserved toasted seeds. Leftovers will keep for 2-3 days if covered and refrigerated.