Tip the drained tuna into a bowl and add the sriracha, mayo and yoghurt with the zest of the lemon and half its juice. Finely chop the chives and red onion and add to the bowl along with the chickpeas.

Mix everything together and season with salt. Add more hot sauce if you like it spicy.

Thinly slice the cucumber and lay over the rye bread. Top with a scoop of your tuna mixture and sprinkle with black sesame. Cut the lemon into wedges and serve alongside.