For the bechamel:
Sauté onion, when we see that it's catching color, add the tomato paste and let it do, when cooked add the tomato Txangurro. For the bechamel, will melt the butter in a saucepan over medium heat. Once melted and starts to sizzle, add the sifted flour and beat with the help of a rod until all lumps are gone and the mixture turns a light brown color. Add the hot milk gradually and continue beating until it begins to thicken. We took it to a boil and let cook for 8 minutes, or until sauce thickens, stirring constantly. Remove from the heat, add the salt, pepper and nutmeg. We tried for whether to rectify and remove anything until we going to use (which we can not use freeze). As we make the bechamel, we cooking the cannelloni (about 5 minutes), once the time will draw water and extend in a cloth to dry, fill with crab meat and cover with bechamel. We will use to decorate some tomato.