Questions & Answers about De portie is veel te groot voor mij.
Why do we use veel te groot instead of just te groot?
Adding veel (much) before te (too) emphasizes just how excessive something is. Just like in English, it changes "too big" into "much too big" or "way too big".
Why use mij instead of the unstressed me at the end of this sentence?
You could absolutely say voor me, but using mij puts a bit of extra emphasis on the fact that the portion is too big specifically for you, which is very natural when comparing your appetite to a standard serving size.
Is there a trick to remembering whether it is de or het with portie?
Yes! The word portie ends in -ie. In Dutch, nouns ending in -ie are almost always de-words.
Since the current lesson covers fractions, how could I use one to ask for a smaller amount here?
You could follow this sentence up by asking for half. You can use the noun form de helft (the half) by asking Mag ik de helft? (May I have half?). Alternatively, you can use it as an adjective: Ik wil een halve portie (I want a half portion).