Put a pan of salted water on to boil. Trim the dry ends off the rhubarb and the chop it into dice around ½cm across. Pop in a bowl. Dice half the cucumber to match the rhubarb and add to the bowl. Finely grate in the orange zest and squeeze in the orange juice.
Finely chop the coriander stalks (keep the leaves to one side for later) and stir them into the rhubarb and cucumber mix. Add the honey with a pinch of salt and stir well to mix. Set the rhubarb salsa to one side for at least 10 mins to mellow.
Scrub the potatoes and chop them into equal-sized chunks. When the water is boiling, add the potatoes and simmer for 15-20 mins till the potatoes are tender when pierced with the tip of a knife.
While the potatoes simmer, trim the roots and top 1cm off the spring onions. Halve them widthways, and then lengthways so you have 4 chunks of spring onion each. Set aside.
Place the chicken breasts between 2 sheets of cling film or baking paper. Bash with a rolling pin or pestle so they are around 1-2cm thick. Rub each chicken breast with ½ tbsp oil each and season with salt and pepper.
Heat a griddle or frying pan over a medium-high heat for 2 mins. Add the chicken breasts and fry for 6-7 mins till golden brown underneath. Flip them over and fry for another 6-7 mins till well browned and cooked through – there should be no pink if you slice into the thickest part of the chicken breasts. Pop the chicken on a warm plate, loosely cover with foil and leave to rest for a few mins.
Add the spring onions to the frying pan and fry for 3-4 mins, turning occasionally, till lightly charred.
While the spring onions cook, tip the salad leaves into a bowl and toss with ½ tbsp olive oil and a pinch of salt and pepper.
Drain the potatoes. Serve the chicken breasts with the potatoes, salad leaves, remaining coriander and charred spring onions. Drain any excess liquid off the rhubarb salsa and spoon the salsa over the chicken to finish.