Preheat your oven to 180°c. For the salsa verde, place the garlic and anchovies into a blender and blitz until Smooth. Add the capers and gherkins and roughly blend before adding the Dijon mustard and red wine vinegar. Pour that mixture into a bowl. Chop all the herbs by hand, fold into the blended dressing and stir in the oil. Correct the seasoning before pouring into a jar and keep in the fridge. Remove and serve at room temperature when needed. This salsa will keep for 3-4 days in the fridge if tightly covered. For the tart case, grease a 24cm tart case with removable base with a little oil or butter. Roll out the pastry on a floured surface and line the tart case well. Leave the excess pastry hanging over the edge of the case. This can be cut off using a sharp knife once cooked to leave you with a clean edge on your tart and prevent the pastry from shrinking whilst baking. Leave to rest, before lining with grease proof paper and baking beans. Place the tart case on to a tray and blind bake for 15 minutes. For the tart filling, blanch the watercress in boiling salted water and refresh, then chop and place into a mixing bowl along with the eggs, Philly, crème fraiche, lemon zest and juice, and seasoning. Whisk until all is well combined and slightly fluffy. Flake the cooked salmon into the base of the part cooked pastry case and pour the liquid mixture on top. Return to the oven for 25-30 minutes. Once golden brown and slightly risen, remove the tart from the oven and allow to cool. Trim off the excess pastry from the sides and remove the tart from the case. Slice the tart into 6 portions and serve with a small tender leaf salad and a spoonful of the salsa verde.