Rinse the beet greens well, and leave the water clinging to the leaves.
Melt the butter in a medium-size skillet. Add the greens and lemon juice, cover, and cook over low heat for 5 minutes. Then add the shallots and salt and pepper. Stir well, cover, and cook until the greens have wilted, another 4 to 5 minutes. Adjust the seasonings if necessary, and serve im