Peas, asparagus, arugula, leeks. This one-pan pasta features allll the fresh greens.
In a large deep skillet, heat the oil over medium. Add the leeks and garlic; cook, stirring often, until softened, about 2 minutes. Add the stock, 1/2 cup water, and 2 tsp. salt. Bring to a boil over high. Add the pasta; cook, stirring often, until almost al dente, about 6 minutes.
Stir in the asparagus and peas. Cook until the pasta is al dente and the vegetables are crisp-tender, about 3 minutes. Stir in the arugula.
Off heat, stir in the crème fraîche, lemon zest, and tarragon; season with salt and pepper.