To a food processor (or high speed blender for smoother texture) add in the Vegan Mayo, or Unsweetened Vegan Yogurt. I actually like doing half a cup of each. If you do all yogurt, you may need to adjust the lemon juice depending on how sour the yogurt is.
For the herbs, I like doing about 1 cup (40g) of Italian Parsley, and then a half cup (20g) each of Dill and Basil. Then finish that off with the chives. Feel free to tailor this to your tastes! You can also use some Mint or Tarragon.
If you can, I recommend weighing the herbs, but at the same time, you can really add or subtract as much as you'd like. Stems are okay to use as long as it's the tender parts.If you are measuring them with cups, I suggest packing them in tight! Add the rest of the ingredients to the food processor and blend for about a minute until it's well incorporated.
Taste and adjust for seasoning of course!
This is great right away, but you can also store it in the fridge for 3 - 4 days. If it thickens too much in the fridge, you can either let it come to room temp or whisk in a tablespoon of water at a time until it's at your desired consistency.