Drain the shredded cucumber in a sieve (placed over a bowl). Heat the avocado oil in a frying pan and add the chopped chard stalks. Cook over medium-high heat for about 2-3 minutes, or until softened. Add the chopped leaves and cook for another 1-2 minutes, or until soft and wilted. Season with salt. Let cool completely and transfer to the sieve with the cucumber (over the bowl to catch the liquid: you can drink this, or add it to a smoothie or chilled soup). Press to drain the liquid.

Combine yogurt, garlic, cumin, turmeric, cayenne and mint in a bowl. Add the chard and cucumber, mix well and season with lemon juice, salt and pepper. Transfer to a serving bowl.

Wash and clean the dipping vegetables. Remove stem and seeds from the bell pepper and cut into long sticks, and cut the celery stalks the same size as the bell pepper sticks. Slice the sunchokes and radish. Arrange on a plate around a bowl of rainbow chard tzatziki.