In a small bowl, cream the butter with the cilantro. Lightly butter each slice of bread.

Spread a little of the tomato on 10 slices of the bread and dust with the bacon. Thinly slice the avocados and arrange over the bacon.

Top each sandwich with a slice of buttered bread. Trim the crusts and cut in half diagonally.

Pack in an airtight container, covered with damp paper towels. Close tight until ready to serve.