Fill a bowl with cold water and dissolve enough salt in it to make it taste like the ocean. Submerge the clams in the water. Let them sit for 10 minutes or until they spit out their grit. You should see sand at the bottom of the bowl. Lift out the clams and transfer to a colander. With a stiff-bristled brush, scrub them vigorously until their shells are really clean.
Heat a medium saucepan over medium-low heat. Coat the bottom with oil and add the garlic and bay leaf. Cook, stirring continuously, until very aromatic, bubbling, and golden, about 4 minutes.
Add the clams and toss to coat in the mixture and get a sizzle going on them. Add the vinho verde and cilantro sprigs. Cover, raise the heat to medium-high, and cook, shaking the pan frequently, until the clams start to open. The liquid should be boiling vigorously. Start pulling out the early birds that open first and transfer them to a dish. Cover the pan again and continue cooking and pulling until all the clams open.
After 5 minutes more, any clams that don’t open are dead; throw them out. Discard the bay leaf and cilantro sprigs. Strain the sauce into a large serving bowl.
Swirl in a little olive oil, then fold in the clams and sliced cilantro. Serve immediately with plenty of crusty bread.