Grate the English cucumber using the large holes of a box grater.
Place the grated cucumber in the center of a clean kitchen towel or several layers of paper towels. Gather the towel around the cucumber and squeeze firmly over the sink until you have removed as much liquid as possible.
Add the silken tofu, lemon juice, apple cider vinegar, garlic, onion powder, sea salt, and black pepper to a small blender. Blend until completely smooth and creamy.
Transfer the blended tofu mixture to a bowl. Stir in the drained cucumber, fresh dill, parsley, and lemon zest.
Cover and refrigerate the vegan tzatziki for at least 30 minutes before serving.
Notes
Squeeze the cucumber thoroughly to prevent watery tzatziki.
Don't press the silken tofu. Simply drain any excess liquid from the packaging.
Blend the base before adding the cucumber. This creates a silky sauce while preserving the texture of the cucumber and herbs.
Zest the lemon before juicing it. It's much easier than trying to zest a soft, squeezed lemon half.
Taste the sauce after it's chilled in the fridge for at least 30 minutes to let the flavors meld.
Store vegan tzatziki in an airtight container in the refrigerator and use it within four days for the best flavor and texture. Stir well before serving. Freezing is not recommended.