Growing for the taste

Imagine that  you're deciding what to eat today - maybe its inspired by a recipe or something that you often make and enjoy. With experience, you know that there are some ingredients that aren't essential and you can replace them with something else which will have a similar taste or texture. 

Now the pedants will say that if the recipe requires an onion, it has to be an onion - not a leek, spring onion or the leaves of elephant garlic.
Similarly if it requires cabbage, it can't be kale, cauliflower leaves or sprouts. 
Spinach must be spinach - not chard or beetroot leaves. 
A salad must have lettuce........

All year round I can pick leaves of spring onions, leeks and elephant garlic, chard, cut and come again lettuce, rocket and various other salad leaves. They're all quite easy to grow and undemanding. 
However, I struggle with cabbage, cauliflowers & sprouts, broccoli, bulb onions and heading lettuce.

So why put myself through all the work and expense when I could grow the taste substitutes with relative ease.

Suggestions welcome for other easy taste substitutes.