A liaison (as a cooking term) describes a thickening agent, such as a butter-flour roux, which is used to thicken sauces and soup. A really wonderful liaison is custard — egg yolks and cream — which thickens and transforms a sauce into a delicious concoction with a delicate and voluptuous mouthfeel. Custard sauces are tricky because the egg sets at 180 degrees, but separates into a curdled appearance at 190 degrees. The sauce absolutely cannot be overcooked, or the result is disastrous. Sorry, no, this soup cannot be reheated or the liaison is lost, but the soup is delicious served cold. Perhaps this dangerous liaison is the perfect one-night stand!

Spinach Soup

• 2 tablespoons butter
• 2 garlic cloves, minced
• 1/4 cup dry vermouth
• 4 cups julienned fresh spinach leaves
• zest of one lemon
• 2 cups chicken stock
• salt and pepper to taste
• 2 egg yolks
• 1/2 cup heavy cream

Melt the butter and gently saute the garlic until tender, but not browned. Add the vermouth. Add the spinach and lemon zest. Add the chicken stock and seasonings. Bring to a boil and cook until the spinach wilts, about a minute. Whisk together the yolks and cream. Ladle a cup of hot broth into the cream mixture to temper. Pour the cream into the hot soup and, while stirring constantly, cook for a minute until the soup slightly thickens and reaches a temperature of 180 degrees. Do not let the soup boil! Serve immediately or transfer out of the saucepan so it does not continue to cook.