2 tablespoons olive oil
1 medium red onion, thinly sliced (about 3/4 cup)
Kosher salt and freshly ground black pepper
Pinch of dried red chili flakes
3 minced cloves garlic minced or grated with a microplane (about 1 tablespoon)
1/4 cup white wine
4 cups homemade vegetable or chicken stock or store-bought low-sodium broth
1 pound dried linguini, broken in half
1/2 cup chopped fresh parsley leaves
2 cups halved cherry tomatoes
2 pounds littleneck clams or manila clams, scrubbed
1 tablespoon zest and 2 tablespoons fresh juice from 1 lemon

Heat the oil in a 12-inch skillet over medium-high heat until hot. Add the onion and a pinch of salt and cook until the onions soften, about 3 minutes. Add the chili flakes and garlic and cook until the garlic becomes fragrant, about 30 seconds more. Add the white wine and stir together. Add the stock to the pan with the linguini and adjust the heat to maintain a vigorous boil and cook until the pasta has begun to soften and is halfway through the cooking process, about 5 minutes. Then add half of the parsley and half of the tomatoes and stir to combine. Add the clams, cover and cook until they open, 6 to 8 minutes, making sure to stir and scrape the bottom of the pan so nothing sticks. Discard any clams that do not open. Finish with the lemon juice and zest, black pepper and the remaining parsley and tomatoes. Season to taste with salt and serve immediately.