Grind the cumin, coriander and fennel in a mortar and pestle as finely as you can.
Place a large frying pan over a low heat. Add 2 tsp of olive oil and add the onion, garlic and spices and cook until the onion is golden and soft. Remove from the heat and place in a large salad bowl.
Finely chop the cauliflower. I like to use the stalks too, but is up to you if you prefer to use the florets only. Increase the heat of the frying pan to medium high and add 1/3 of the remaining oil. Fry 1/3 of the cauliflower until golden and tender. Remove from the heat and add to the onions. Cook the remaining cauliflower and place in the bowl with the onions. Add the lemon zest and juice, along with the chickpeas and toss to combine and leave to cool completely.
Wash out the frying pan and dry it completely. Place the pan over a medium heat and add the buckwheat. Toast for 3 to 4 minutes until golden and fragrant. Leave to cool.
Before serving toss through the baby kale and season with salt and pepper. Sprinkle the toasted buckwheat over the top.