Must One Eat a Kezayit of Bread for the Hamosi to Exempt Other Foods?

The Beracha of Hamosi recited on bread exempts all foods that one normally eats in the course of a meal. Hacham Ovadia rules that this only applies when a person eats at least a Kezayit (olive's bulk) of bread. However, if one recited Hamosi on a small quantity of bread, the Beracha does not exempt other foods that he subsequently eats. In such a case, he must recite a separate Beracha on them and recite the appropriate Beracha Aharona, as well. This commonly occurs at weddings where they serve small pieces of bread garnished with vegetables and oil. Even if one made Hamosi on this appetizer, it does not exempt the other foods he intends to eat.

SUMMARY
The Beracha of Hamosi only exempts other foods if one consumes at least a Kezayit of bread.