Warm the chicken stock and sage together in a large pot and bring it just to a light simmer, keeping the heat low. prep

Slice each garlic clove lengthwise and remove the inner sprout using a knife tip or toothpick, discarding the shoots. prep

Boil the prepared garlic cloves in a small pot of water for several minutes until softened, then drain thoroughly. prep

Mash the tender garlic into a smooth paste using a fork, then stir it into the simmering stock and cook gently for several minutes. mix

Combine the egg yolk, mustard, salt, and olive oil in a narrow container and blend from the bottom upward until thick and emulsified, adding egg white only if needed. mix

Optional: Pass the soup through a strainer for a smoother texture, returning the liquid to the pot afterward. prep

Slowly whisk a ladle of hot soup into the mayonnaise to warm it, then immediately stir the mixture back into the pot. mix

Reheat the soup carefully until hot, ensuring it does not boil to maintain a smooth consistency. finish