Pasta With Zucchini, Feta and Fried Lemon

pasta, such as spaghetti or bucatini

Kosher salt

olive oil, plus more for drizzling

walnut pieces (optional)

large shallots, 1 medium onion or 1 large leek (white and light green parts), thinly sliced

lemon, thinly sliced, seeds removed

Freshly ground black pepper

capers

zucchini (about 2 medium), thinly sliced

feta, crumbled (about 3/4 cup)

parsley or dill leaves, or a mix, coarsely chopped

fresh oregano leaves