Using an immersion blender, give the pistachios and cilantro a blitz until a somewhat chunky crumb is achieved. Add the capers and 30mL of the olive oil and whizz until an even crumb is achieved.
Whisk together the egg yolk and the minced garlic. Slowly add in the remaining olive oil in small batches, whisking vigorously until the egg and oil are emulsified. Add the lemon juice once about half of the oil has been added.
Combine the pistachio/cilantro crumble with the egg/oil emulsification, then add the balsamic vinegar. Whisk to combine, then add additional oil or water to adjust consistency. Add salt, pepper, lemon juice, and/or balsamic vinegar to taste.