Most soups have origins, but none more so than this Mediterranean one of France, whose antecedent is usually called something like boiled water. At its most impoverished, this is no more than garlic simmered in water to give it flavor, with a few crusts of bread added for bulk. Simple as it is, boiled water is the perfect example of how an almost absurdly elementary preparation can be converted quickly and easily into one that is nearly grand. Use stock in place of water if you have it. This is a fine place for canned stock, because the garlic-scented oil will boost it to a higher level. Remember to cook the garlic very gently to add complexity and color; by then browning the bread in the same oil, you increase its flavor immeasurably. Also consider doubling the amount of bread given in the recipe here; like me, you may find the allure of bread crisped in garlic-scented oil irresistible.
To make a stock from the shrimp shells, put the shells in a pot, cover with water, bring to a boil, and simmer for about 5 minutes; strain. (The liquid can be used in many shrimp dishes or in place of fish stock in most recipes. You can accumulate shells and freeze them over a period of months if you like, and there’s no need to defrost them before making the stock.) The amount of stock made by the pound or so of shrimp in this recipe isn’t enough to complete the soup, but its volume can be increased with water or enhanced with chicken stock; the combination is wonderful.
