What's the best way to clean the dishes?

I wondered as to how that detergent taste permeated into the tupperware.
The answer I came up was; I soaked it overnight.
After using it to put something like pasta sauce and curry, it's really hard to get the smell off plastic. The way I was cleaning it was, leaving it in the mixture of soapy water and baking soda overnight and then rinse it really well.

However, no matter how well I rinse it, the detergent residue that got right into the plastic is difficult to get rid of.
The thing I might try next is to leave it in the mixed solution of lemon juice and baking soda, that way it will be free from any toxin.

Green olive oil soap is good for nearly every cleaning job, but still not strong enough to eliminate the tomato sauce and curry smell.

An anecdote from about a month ago...
One day, I pan-fried a couple of slices of fish for tea (I can't remember the name - something cheap). After cooking I cleaned the pan extra carefully. However, the next day I cooked something else in the same frying pan. My hubby couldn't finish his meal, claiming that it had too much fish taste to it.
By that time I had totally forgotten what I cooked the previous night and just shook my head with my eyes rolling. Then I blankly looked at the frying pan - ah, of course. The Fish. I thought. No, it can't be...I faltered...but why else could he smell and taste the fish?

So here's a question remains. How the hell can I get rid of the food smell???