Put the flour in a mixing bowl, and crack the eggs on top of the flour. Gently start mixing the eggs with a whisk, gradually whisking the flour in, little by little, until it's all incorporated. If it gets a bit thick, add some of the milk to loosen it up. Once all the flour is mixed in, add the rest of the milk, 2 tablespoons of oil and a good pinch of salt. Leave for at least an hour before using.
Heat a large non-stick frying pan and melt a bit of butter (or heat up oil) in it. Pour in a ladle full of batter, swirl the pan around, then pour any loose batter back into the bowl it came from. You should be left with a thin pancake stuck to the pan. Let it cook for a minute or so, flip it over for 30 seconds and then slide it out on to a plate. Repeat until all your batter is used. Let the pancakes cool completely on a wire rack.
The batter should yield about five pancakes, so you could use the remainder for dessert or breakfast.
Make a 40cm x 15cm rectangle of double thickness of cling film and lay two pancakes on it side by side, overlapping. Spread them with a thin layer of crème fraîche, lay most of the chives on top, season well with pepper and place a layer of smoked salmon over the top.
Use the cling film on one of the long sides of the rectangle to roll the pancakes up tightly like a Swiss roll. Re-wrap in cling film and leave for at least half an hour in the fridge to let them firm up before cutting them into slices about one inch thick. Sprinkle with the remaining chives before serving.
Serve with a dip made from the rest of the oil, the lemon juice and salt and pepper. You could use mustard mayo or even horseradish sauce instead of the vinaigrette dip if you like.