For the nicest effect, use at least two sizes of heart-shaped cutters, the smaller the better.
Cut vegetables into 1/4-inch slices. With the cookie cutters, make tiny hearts.
Blanch for 1 minute, then plunge into an ice-water bath. Drain and set aside, separately wrapped, in refrigerator.
When ready to serve, melt butter in a small saute pan. Add vegetables and cook over medium heat until soft, about 5 minutes. Add salt; garnish plates with hearts.