Baby Beet Tarte Tatin from 'River Cottage Veg'

Ingredients (17)

• 2 1/3 cups (300g) all-purpose flour
• Pinch sea salt
• 1/2 cup plus 2 1/2 tablespoons (150g) chilled unsalted butter, cut into small cubes
• Ice water
• 8 ounces (250g) rough puff pastry (see above) or all-butter puff pastry (ready-made)
• A knob of butter
• 1 tablespoon canola or olive oil
• 2 teaspoons cider vinegar
• 2 teaspoons brown sugar
• Sea salt and freshly ground black pepper
• 10 to 14 ounces (300 to 400g) baby beets (the size of a golf ball or no bigger than a small apple), scrubbed and halved
• 1 or 2 shallots or 3 or 4 green onions, trimmed and very finely chopped
• 1 teaspoon English mustard
• 1 tablespoon cider vinegar
• 1/4 cup (60ml) canola oil
• Pinch sugar
• A handful of parsley leaves, finely chopped