Dear Tofitropic,
thank you for the identification - that's exactly the tree/fruit! Funny thing, that it resembled totally a Gooseberry from ist flavour and a common name seems to be Ceylon Gooseberry. Again thanks a lot!
Dear Daisyl,
thank you for your questions/comments. On the last foto you actually can see a flower below the fruit (it's kind of yellowish green); thanks to tofitropic you can find more details on Wikipedia by looking up "Dovyalis_hebecarpa"
Thanks again and all the best
Hendrik
