Preheat the oven at 180° C. Grease a large oven-proof dish. Remove the stalks from the fennel, rinse it in water and cut it into thin strips. Bring water to the boil in a large pot and add salt. Add 60ml of lemon juice and the fennel. Cover and cook for 3 minutes over a medium heat. Drain and rinse with cold water. Put the fennel in a salad bowl. Add 2 tablespoons of lemon juice, salt, pepper and the Si'doux and mix well. Sprinkle with flour, put the mixture in the baking dish and pour the soy cream onto it. Oat garnish: mix the flakes, the flour and the crumbled bread. Heal the oil in a small frying pan and fry the onion during 30 seconds, until it is transparent. Add the flake mixture and stirr carefully. Spread the mixture over the fennel and put the dish in the oven for 20 to 30 minutes, until the fennel is tender and the garnish is golden brown.