Preheat the oven to 425°F (220°C).

In a large half-sheet pan, toss the peewee or fingerling potatoes with olive oil, kosher salt, and black pepper. Arrange cut-side down and roast for 15 minutes.

After 15 minutes, add the sliced red spring onions on top of the potatoes and roast for an additional 25 minutes.

Once roasted, allow the potatoes and onions to cool for about 10 minutes.

In a large mixing bowl, combine fresh arugula, radishes, and spring onion tops; toss gently.

In a food processor, pulse together arugula, basil, chives, garlic, pine nuts, and Pecorino Romano cheese until finely chopped. Stir in lemon zest, lemon juice, and olive oil, seasoning to taste.

Add warm roasted potatoes and spring onions to the salad bowl, along with the pesto. Toss gently to coat.

Serve warm or at room temperature, adding extra lemon juice or black pepper if desired.