thanks Martin it worked! although I replaced your (SELECT MAX(ID) FROM Properties) by ROWID. is it sound?
like that:
CREATE TRIGGER create_ingredient_property AFTER INSERT ON Ingredients
BEGIN
INSERT INTO Properties (price) VALUES (NULL);
UPDATE Ingredients
SET property_ID = ROWID
WHERE ID=OLD.ID;
END;
-- price doesn't matter. I set it up much later.. (whenever the user want,
in fact), but I want my property line created and correctly linked!

