Shenky! Carrots, beats, lettuce, kale and spinach are so so easy to grow. Listening to potters anti-gardening propaganda was making me scream lol you can do this! Make sure to the soil doesn't dry out and that's about all you really need to worry about. Melons will be tricky but I say do it anyways!
You can grow herbs like basil, rosemary, and thyme. If the box is bigger you can grow carrots, radishes, green beans,. Depending on size you probably can only do 2 or three of those. Good luck
You can for sure grow a blueberry bush. They are not that big. Just make sure you use peat moss in the potting soil mix so that the soil is properly acidic.
Flan is in alot of countries. Japan has their own version though. They all have their own versions of Flan but it is usually made differently with the eggs and the toppings.
