If you want to make this ahead, store in the fridge overnight until needed.
Method
Toast the nigella seeds in a non-stick pan until smelling fantastic. Wash the carrot, then coarsely grate into a bowl. Add the natural yoghurt and nigella seeds. Squeeze in the lemon juice and mix.
Season to perfection, tasting and tweaking. Finish with a kiss of extra virgin olive oil, if you like.