1 T. olive oil
1 tablespoon water
water — 1 liter, boiling and salted to taste
1 egg, separated
pepper to taste
1 teaspoon red wine vinegar
Toast the chopped garlic in the olive oil. Add the flour. Mix well, then cook until the garlic soften and brows a bit. Add the salted water, and cook for 10 minutes. In a separate dish, mix the egg yolk, pepper and vinegar. Add the egg white to the soup, first tempering in a separate bowl with a whisk, so that no large pieces of egg white form. Cook another 5 minutes. Remove from heat and add the egg yolk mixture, again tempering to avoid coagulation. Serves 2.
Top with croutons and a parsley sprig, Serve hot. Bon appétit.
There's a nice article here describing this French classic.