Baked Potato, Buttermilk and Herb Dressing

• 1 large floury potato
• 1 tablespoon Dijon mustard
• 1 garlic clove, crushed

Bake the potato until tender, then cut it in half and scoop out the flesh into a blender. Blitz with the mustard, garlic, oil, vinegar and enough buttermilk to give a smooth, creamy consistency, similar to single cream. Pour into a bowl and stir in the herbs, a good pinch of sugar and seasoning to taste. Pour over hot potatoes and serve.