Radish Butter (for Radish Sandwiches)

6 radishes4 Tbs butter1 tsp lemon zest (optional) Trim the radishes.  If the leaves are tender and fresh, set a dozen or so aside.  Slice the radishes into thin rounds, then crosswise into narrow strips.  Each should be tipped with color.  Chop the leaves.Mix the butter with the lemon zest until it's soft, then stir in the chopped radishes, radish leaves and a pinch of salt.  Spread on slices of bread and serve.