Wash the parsley, shake dry and remove the thick ends of the stem. Then chop up a bit and put it in a food processor. Peel the garlic and add to the parsley. Also add two to three zest of organic lemon. Chop first at medium, then at high speed until a green mass is formed.
Add the oil, drained tuna, half of the squeezed lemon, half a teaspoon of salt and some freshly ground white pepper. Mix everything in at low to medium speed for a few seconds. The pesto shouldn`t get too mushy. Therefore, check the mass more often and mix only briefly.
At the end, season again with salt and pepper.
Pour the pesto into a clean screw-top jar and cover the top with a little olive oil. This will keep it in the refrigerator for a few days.
Tip: Like any other pesto, the pesto is simply lifted under the cooked pasta. If necessary, you should dilute it with a little pasta water, as it is quite thick. Then serve sprinkled with fresh parmesan. It goes best with spaghetti or thin linguine.