01 - Place baby potatoes in a large saucepan and cover with cold water. Bring to a boil, then simmer for 12–15 minutes until fork-tender. Drain completely and allow potatoes to cool for 5 minutes.
02 - In a separate pan, bring salted water to a boil. Add spring peas and blanch for 2 minutes until bright green. Drain immediately and transfer peas to an ice bath; drain again after 1 minute.
03 - Halve or quarter cooled potatoes as needed. In a large mixing bowl, combine potatoes, peas, green onions, dill, and parsley.
04 - In a smaller bowl, whisk together mayonnaise, Dijon mustard, lemon juice, olive oil, kosher salt, and black pepper until emulsified.
05 - Pour dressing over vegetable mixture and gently toss to coat. Adjust seasoning as desired. Serve chilled or at room temperature.