Breakfast smoothie for kids

Oven a year my children have been drinkin smoothie as breakfast. Occasionally they want cereals, or toast, or even (oat)porridge, but eventually they end up wanting smoothie.

Buying smoothie is something I just can't do. I made a wild guess one portion smoothie is about 1,5€, and that's mostly fruits (I checked this from local price comparing site which has also ingredients listed). So 3x1,5€ every day is a bit too pricey for me, and kids would have needed something else to keep their hunger at bay (they eat breakfast about 6.30am and have school lunch at 11am or at noon - that's more than five hours between meals).

I've made this same smoothie with small variations over 200 times now!

Breakfast smoothie (2 portions á 3dl) in Ulv's Lair:

1 rather big banana
handful of frozen strawberries
1dl of frozen lingonberries
1dl of frozen currants (kids prefer black currants, but white and red will do, haven't got any green but I guess they'll do, too, because they taste a lot like black currants)
two small handfuls of oats (instant oats are fine, as well as rolled flakes of other grains like rye, barley, wheat - not cereals but ones ment for porridge)
vanilla yoghurt (or plain yoghurt and some vanilla)

I thaw frozen berries in microwave oven for about a minute, then toss everything into bender. Never used frozen bananas and never ever have I added ice to this smoothie!
Banana brings sweetness which children like (excluding os who is allergic to bananas). I ran out or lingonberries last spring, and kids weren't happy. I almost went to Ikea to find lingonberries! My colleague brought me some in autunm so now I have their dose of tartness again.

I have found that banana, strawberries, lingonberries and currants make the best mix. Usually I add some other fruits (apple, pineapple, pomegranade, plums etc) or berries, what I have in hand. Sometimes I add zucchini, or kale or spinach or chard. Or pinch of dried nettles. I have added ground crickets, too. Anything that blends well.
Oats are needed because they keep hunger away (as well as yoghurt).
Sometimes I add milk, or orange juice (or any other juice I happen to have), or if I don't have yoghurt, I use buttermilk.

It is easy to make this too thick, but it is easily solved by adding more fluid, like juice or milk.
This thickens in fridge, so in the evening spoon is maybe needed. My children drink this with stainless steel straws they got a year ago at christmas.

And last but important note: rinse bender right away or this will stick to it forever. Also rinse straws immediately after use. So much easier.