Horseradish and preserved lemon salmon roulade

• 350 gr long slice smoked salmon
• Vegetable oil for greasing
• 60gr plain flour
• ½ tsp bicarbonate of soda
• 1 tsp salt
• 1 large free-range egg
• 150ml whole milk
• Small bunch fresh dill, roughly chopped

For the herb paste:

• Large bunch fresh parsley
• 2 x small bunches fresh chives, roughly chopped
• Finely grated zest 1 lemon, plus juice ½
• 4 tbsp extra-virgin olive oil

For the cream cheese filling:

• 460gr Philadelphia cream cheese
• 2 tbsp creamed horseradish
• 4 preserved lemons, flesh discarded and peel finely chopped