Dicing / chopping on Shabbos

Can I chop/dice vegetables using a knife without regard to how small I’m dicing on Shabbos ?

Not a problem

What about טוחן one of the 39 melachos of shabbos

Why dont you say you need מיד סמוך לסעודה
Or else there would be a violation of טוחן and in many instances בורר

As long as youre doing it for the meal its fine, it does not have to be right before the meal.

You need מיד look Rema in siman שכא סעיף יב

Rabbi Abadi considers דק דק to be extremely small. Something most of us can’t do. That’s why it doesn’t need to be מיד