1.To poach eggs, half-fill a large wide saucepan with water, add vinegar; bring to the boil. Break 1 egg into a cup. Using a wooden spoon, make a whirlpool in water; slide egg into whirlpool. Repeat with another 3 eggs. Allow water to return to the boil. Cover pan, remove from heat; stand about 4 minutes or until a film of egg white sets over the yolks. Using a slotted spoon, remove eggs one at a time from pan; drain on absorbent paper. Repeat with remaining eggs. Trim eggs into a neat shape.
2.Bring stock and milk to the boil in medium saucepan. Gradually add polenta; cook, stirring occasionally, about 20 minutes or until polenta is soft. Stir in cheese, butter and oil to taste. Season to taste. Remove from heat; cover to keep warm.
3.For salsa verde, peel and crush garlic. Finely chop anchovies, capers, herbs and rocket; combine with garlic, oil and juice in medium bowl. Season to taste.
4.Serve polenta topped with eggs and salsa verde.
Salsa verde can be made a day ahead. Keep the surface tightly covered with plastic wrap and store in an airtight container in the refrigerator. Stand at room temperature for 30 minutes before serving for better flavour. Polenta can be made up to an hour ahead; reheat, adding a little extra stock to achieve a soft runny consistency, if needed. Truffle oil can be bought from most delis – it is expensive but only a little is required to achieve that special flavour. Omit it if you prefer.