My mali was addicted to dandilions when we first had him, mainly becasue we spoiled him. The thing is that uro's can be picky eaters, but you still have to push them to eat their greens. I find that if you tear up the flower into pieces and mix it in with the chopped up greens, they are unable to just pick out the yellow without eating some greens too. Spring mix is great, just make sure that it doesn't have spinach, as it can bind the calcuim in their bones. Thankfully, dandilions are a healthy food, but they are not always available, especially in cold weather or in droughts. Another tasty treat are peas, again, to be used in moderation.
Key thing is they are just like a child, when it comes to eating habbits. You have to build their taste by exposing them to new things and making it impossible to get the tasty parts they want without eating the greens that they don't like (yet). Eventually, they learn to eat a variety of food. Good luck!