Cut the shallot into thin strips and the rhubarb into sticks about 5 cm long. Heat 1 tbsp olive oil in a non-stick frying pan. Sweat the shallot, add the rhubarb and cook briefly, seasoning and adding the thyme. Set aside.
For the cauliflower rice: cut the cauliflower into florets, place in a blender and blend briefly to obtain cauliflower rice.
Cut the chard into small pieces and add to the cauliflower.
Heat 1 tbsp olive oil in the same non-stick frying pan, add the cauliflower rice and the chard and cook for around 10 minutes over a medium heat. Season and serve with the salmon topped with the rhubarb.