Pasta Primavera with Crispy Onion Gremolata

Cook spring onion bulbs and oil in a small saucepan over medium heat, swirling pan occasionally, until bulbs are golden brown, about 3 minutes. Transfer bulbs to paper towels with a slotted spoon to drain; season with salt. Set aside 2 Tbsp. onion oil.

Combine spring onion bulbs, chives, and 1 Tbsp. lemon zest in a small bowl; set gremolata aside.

Cook fava beans in a large pot of boiling salted water until tender, about 2 minutes. Transfer to a colander set in a bowl of ice water with a slotted spoon or mesh spider. Drain and peel, transferring to a medium bowl as you go. (If you’re using frozen fava beans, you won’t need to peel them.)

Return water in pot to a boil and cook asparagus until tender, about 1 minute. Transfer to colander in ice water with slotted spoon. Drain and add to fava beans.

Return water in pot to a boil and cook pasta, stirring occasionally, until very al dente (pasta will still be opaque and very firm in the center). Drain pasta, reserving 1½ cups pasta cooking liquid.

Meanwhile, heat reserved onion oil in a large skillet over medium-high. Add spring onion stems, garlic, and mushrooms; season with salt. Cook, stirring often, until vegetables are tender and beginning to take on some color, about 4 minutes. Stir in crème fraîche, ½ cup pasta cooking liquid, and remaining 1 tsp. lemon zest and bring to a simmer.

Add pasta and ½ cup pasta cooking liquid and cook, tossing often and adding more pasta cooking liquid as needed to help finish cooking pasta, until pasta is al dente and sauce is thickened and coats pasta, about 5 minutes. Add fava beans, asparagus, and lemon juice and toss to combine; season with salt and pepper.

Serve pasta topped with onion gremolata.