Question: What is the average number of dishes per menu in the Souper de Luxe menus? Identify what is the name of the dish that appeared the most in all of its menus.
SQL: SELECT COUNT(*), T1.dish_id FROM MenuItem AS T1 INNER JOIN MenuPage AS T2 ON T1.menu_page_id = T2.id INNER JOIN Menu AS T3 ON T2.menu_id = T3.id INNER JOIN Dish AS T4 ON T1.dish_id = T4.id WHERE T3.name = 'Souper de Luxe' GROUP BY T3.id ORDER BY COUNT(T1.dish_id) DESC LIMIT 1