Add the grated cheese and red onion to a mixing bowl.
Next add the chives, mayo and nutritional yeast.
Now add the lemon juice and season with salt and pepper, then mix well.
Give the flavours 10 minutes to develop before making your sandwiches or cover the bowl and pop in the fridge until you need it.
If you are making sandwiches with sandwich filler from the fridge, allow it to come to room temperature before making them as the chill from the fridge can deaden the flavours.
Add to buttered bread and add salad leaves if you like, serve and enjoy!
Notes
If you are very generous with the filling this may make 3 sandwiches and not 4.
If you don't have nutritional yeast you can skip it or replace it with grated vegan cheddar.
You could also try this sandwich filling with vegan salad cream instead of mayo.
For a pop of heat, why not add some paprika and chilli flakes.
You can keep this filling in the fridge for 3-4 days.