I have oven roasted beets on many occasions, wrapping washed, unpeeled beets in foil and have never had a problem. This weekend, following Patrick O'Connell's recipe for a beet carpaccio I tossed beets with olive oil, balsamic vinegar, sprigs of thyme and rosemary and put them in the oven in a foil covered roasting dish. After the suggested time of 40 min I checked them, took the easily pierced ones out and put the remainder back in. I did this several times as they were quite varied in size. Rather than getting softer with time the larger beets got hard and the ones I thought perfectly cooked also became hard and IMPOSSIBLE to peel. What could have happened ??
Mamma Mia !