1 tablespoon extra-virgin olive oil
4 ounces pancetta, diced
½ medium onion, diced
1 large carrot, peeled and diced
1 celery stalk, diced
1 pound asparagus, ends snapped off and discarded, stalks and tips thinly sliced
2 garlic cloves, smashed and minced
1½ teaspoons herbes de Provence (a blend of thyme, rosemary, marjoram, savory, basil, fennel seeds and lavender)
1 teaspoon kosher salt
¼ teaspoon freshly ground pepper
½ cup dry white wine
4 cups chicken stock or low-sodium chicken broth
2 cups peas (1¾ cups freshly shucked peas plus ¼ cup frozen [not thawed], or all frozen)
¾ cup (loosely packed) fresh Italian parsley leaves
1 piece standard sandwich bread, torn into rough pieces
1 cup plain whole-milk yogurt (not Greek)
½ teaspoon cornstarch
1 tablespoon cold water
Heat a Dutch oven or soup pot over medium-high heat. Add the oil and pancetta. Cook, stirring, until the meat is browned and crisp, 6 to 8 minutes. Remove with a slotted spoon to a paper towel–lined plate. Add the onion, carrot, celery, asparagus, garlic, herbes de Provence, salt and pepper to the residual fat in the pot. Lower the heat to medium and cook, stirring occasionally, until tender and just beginning to color, 12 to 15 minutes. Add the wine, bring to a boil over medium-high heat, and let bubble for a minute or two until most of the liquid has evaporated and only a thin sheen remains. Add the stock and 1¾ cups of the peas and return to a boil. Reduce the heat to medium and simmer until the peas are tender, 5 minutes longer. Remove the pot from the heat. Stir in the parsley, bread and the remaining ¼ cup frozen peas. Using caution, purée the soup in a blender in batches, or use an immersion blender in the pot. Return to the soup pot, if necessary.
Place ¾ cup of the yogurt in a small bowl. In a second small bowl, whisk the cornstarch with the water. Whisk this slurry into the yogurt to combine thoroughly. Whisk ¼ cup of the soup into the yogurt mixture to temper, then scrape the mixture into the soup pot. Whisk to combine. (Reheat gently, if necessary, but do not let the soup boil.)
Divide the soup among 6 bowls. Divide the remaining ¼ cup yogurt among the bowls, in dollops. Sprinkle each dollop with the crispy pancetta. Serve immediately.
Avoid low-fat and nonfat yogurt, which will cause the soup to break.