Halve the avocado, remove the stone and scrape out the pulp. Mash well together with the lemon juice with a fork, mix in 1-2 tablespoons of tzatziki and season with salt. Fill into a bowl and let it steep, but it can also be served immediately.
The amount of tzatziki and lemon juice depends a bit on the size of the avocado. Lemon is important because the avocado turns gray quickly. If you put the core in the mass and cover it well, the guacamole will not tarnish so quickly.