With the last lines of the novel, we are left in the hands of Tita's grand-niece, who states:
[…] perhaps I am as sensitive to onions as Tita, my great-aunt, who will go on living as long as there is someone who cooks her recipes. (12, 867)
Hmm, well, if that's true, maybe we can gain some closure in the fact that Tita dies so suddenly. While she's not with us physically, her memory is alive in her recipes and alive in her food, which has been passed down to her grand-niece. Not to mention the fact that she died in a moment of ecstasy (orgasm) and will spend the rest of her after-life with Pedro.
Love. It conquers all. Even death.
Food. It makes us cry (dang, onions) it makes us laugh, it can even make us throw up (we'll pass on the wedding cake, thanks). It's nourishing to the body and the soul, and the ending in Like Water for Chocolate is true to both notions.