Cut the cucumber in half vertically. Scoop out the soft part, then cut the hard flesh into half moon shapes. Put these in a bowl and drizzle with the sesame oil, rice vinegar and soy sauce. Add the sesame seeds and toss.
In a medium bowl, lightly whisk the eggs with the soy sauce and sesame oil. Set aside.
Finely chop half of the chilli - thinly slice the other half into rings. Add the sliced chilli to the relish and toss.
Cut the spring onions into tiny bits ( including the green part). Stir a handful of it into the relish, put the rest into a frying pan.
Roughly slice the pak choi then add to the pan. Add the chopped chilli & sesame seeds, pour over the oil, then heat it up gently and stir-fry for 5 -8 minutes until soft.
Pour over the egg mixture, letting it spread out evenly. Put a lid on, and gently steam over low heat for about 8 minutes until the top has set.
If you want it to be a frittata, heat the grill or oven and brown the top.
Serve warm with the relish scattered on top, drizzled with soy sauce.
Or let it cool and slice it into wedges or bite-sized cubes and serve with the relish on the side.