New Potato Salad with Spring Onion Pesto

Name: New Potato Salad with Spring Onion Pesto
Ingredients: 1/4 Cup white-wine vinegar; 1 Tablespoon kosher salt; 1 1/2 Teaspoon sugar; 1/4 Cup water; 1 large bunch spring onions or ramps, green and white parts separated; 2 1/2 Pounds Peruvian purple potatoes, halved, or whole fingerling potatoes; 1/2 Cup pine nuts, toasted; 1/2 Cup grated Parmesan; 3 cloves garlic, peeled; 1/4 Cup olive oil; 1 Cup coarsely chopped parsley; Juice of 1 lemon; 1/4 Teaspoon freshly grated nutmeg; Salt and pepper, to taste