Method:
Step 1: Cook the potatoes in boiling salted water for 15-20 minutes or until tender.
Step 2: Place the mustard, vinegar and a tablespoon of water into a blender with seasoning and blitz until emulsified.
Step 3: Slowly add the sunflower oil in a thin steady steam and then add enough water to make a coating consistency.
Step 4: To make the rissoles, chop the beef and onion in a food processor using the pulse button (mixture should be finely chopped but not a paste).
Step 5: Transfer to a bowl and add the fresh breadcrumbs, mustard, horseradish, parsley, garlic, egg and season to taste.
Step 6: Divide into 12 portions and shape each into a round patty with your hands. Coat with the dried breadcrumbs.
Step 7: To cook the beef rissoles, heat a thin layer of sunflower oil in a non-stick saute pan and cook the rissoles for 4-5 minutes on each side. You may have to do this in batches depending on the size of your pan.
Step 8: Drain the potatoes and when cool enough to handle cut them into slices or chunks depending on their size. Transfer to a bowl and sprinkle over the chives, then fold in enough dressing to lightly coat.
Step 9: Just before serving lightly dress the spinach in a little more of the dressing and gently fold into the potatoes. Arrange the beef rissoles on warmed plates with some of the warm potato and spinach salad to the side to serve.