If Americans are squeamish about eating blood, we’re much in the minority, at least among countries where it’s not religiously prohibited. People eat blood around the world in all kinds of ways: from France’s rich, gamy sauces and Spain’s morcilla to Swedish blood pancakes, British black pudding and the chocolate-laced blood sweets of Italy; in sausages and stews throughout Southeast Asia; in the wobbly slabs of blood tofu that are a key element in China’s hot pots and soups. Yet in the United States, most blood from slaughterhouses is processed into animal feed and fertilizer. In this era of nose-to-tail dining, when we pat ourselves on our sustainable backs for every ear, liver or trotter we dare to eat, why do we routinely pour the most vital part of the animal down the drain?