First cut the rhubarb into chunks, and put them in a big enough saucepan. Add the sugar and about 1/2 cup of water to get it going. Put it on the stove, bring to the boil and once boiling, turn down the heat, put the lid on and leave to simmer for about 10 minutes or until the rhubarb is soft enough. Leave to cool
Make your sugar syrup by putting about 110 gr of sugar and 180 ml of water in a small saucepan. Stir over low heat until the sugar is dissolved. Then increase the heat and boil for 1 minute. Set aside to cool completely. (makes about 250 ml so you will not need it all!)
Clean and peel your mango, remove the stone and cut into chunks and put into a blender. If there is not enough moisture to keep the blender or foodprocessor going, you can add a little bit of vanilla yogurt or orange juice to get it going. Water would also work! Once pureed, taste and add sugar syrup if you need to. Put the mango through a sieve to remove any unwanted bits
Put the rhubarb also through a sieve so you're left with a smooth puree.
Take your popsicle moulds and pour the mango in first. leave some space to add the rhubarb on top. You can mix it in carefully with a wooden skewer or leave as is.
Set in the fridge for at least 4 hours or preferably overnight.
Notes
Please note that the nutritional value contains the entire quantity of sugar syrup. You will likely only add a bit of this into the popsicles.