I have been experimenting with my esbit stove ( maybe not geniouine esbit, but anyways). I made some Cup-A-Soup. and some coffee. I tested one tab of fuel, 2 tabs, and then 3 tabs all together.

I noticed that 3 tabs was overkill . The flame was like ( too much fuel and little oxygen). It made my pot blackish. Two brought the pot to a rolling boil, and one tab didn't. However, I wondered : why do we need water to boil. In any case we will have to wauit for it to cool a bit before drinking it. So, I am planning to use one tab only even if water won't boil completely. It only needs to boil if you are sterilizing water or cooking something. IN other cases, you need temp to go up and hover below boiling for a few minutes.

My soup was a mix of lentil soup , French onion, vegetable, and mushroom. About one spoon each , then added water, stirred, and covered for 10-15 minutes. It was tasty and rich enough for a lunch.

The next time I am only using one tab of fuel.

About coal briquettes in the esbit stove, well, their heat was minimal and only useful to keep water from cooling down. I am thinking to ditch the coal briquettes and carry more esbit tabs next time.

My problem is ... I only have a finite stock of these tabs. That is why I tried to stretch them with coal briquettes in the first place. However, the good news is that I had some real old fuel tabs (became yellowish) but they still burnt cleanly. This means they can be stored for many years ( in our HOT environment). This is encouraging.