How do I say "One day on a sunny Sunday morning" in German?
Eines Tages eines sonnigen Sonntagmorgens bin ich mit meiner Schwester im Park zum Training gelaufen.
Don't we already know it's sunny because it's Sunday? Just kidding :)
So there is the literal translations:
But this versions are not really good style as both, "Eines Tages", and "ein sonniger Sonntagmorgen" are an expression for the same indefinite day.
So we'd probably say something more along the line of
or, if we need the day for an accurate translation