Onions peel and cut into slices. Add bacon and peppercorns to about 1 1/4 litre of lightly salted water. Bring to the boil and cook in a closed saucepan over medium heat for about 45 minutes.
15 minutes before the end of the cooking time, add beans and pears to the bacon and season with savory. Remove the bacon and pears. Cut bacon into pieces. Cut pears in half lengthwise. Stir the starch in a little water until smooth and bind the simmering stock with it until slightly creamy, bring to the boil again.
Season to taste with a little salt and pepper and put the pears and bacon back in. Arrange on preheated plates and garnish with savory if desired.