Heat a frying pan and melt 20g of butter.
Season trout with salt and pepper and add to the hot pan.
Fry for two minutes, flip, fry for one more minute, then set aside.
In a separate pan, melt remaining butter and stir-fry rhubarb with sugar and ginger until softened.
Remove crusts from bread and cut into 1cm cubes.
Heat olive oil in a pan and fry bread cubes with seasoning until golden.
Drain the croutons on kitchen paper.
Whisk lemon juice, zest, mustard, salt, pepper, and extra virgin olive oil in a bowl.
Toss mizuna, spinach, parsley, and croutons with the dressing.
Serve trout topped with rhubarb alongside the salad.