In a bowl, whisk together the labneh, cheese, mayonnaise and mustard along with the salt and butter till a nice thick mixture.
Take half of it and toss along with the cucumber, carrot and coriander leaves. Season well.
In a long plate, layer two bread slices. You may remove the slices or keep it. Spread on layer of the vegetable mix.
Top with two more slices of bread and repeat till done. Use the leftover to cover on the top and sides.
Use the remaining labneh mix to cover the whole "cake" on the sides and top.
Transfer into a fridge for around two hours for the flavors to settle. Sprinkle up the coriander leaves on top, slice up and enjoy as your afternoon tea.