Baking Soda – How to Create a Water and Baking Soda Solution? Uses and Benefits

Unless you hot-desk (and even then, with a bit more effort) it should be possible to take your own mug to the office and use that to microwave instead of a styrofoam cup. Note that it's worth being a bit cautious when adding anything to water microwaved to boiling point - I would use a spoon to insert the tea without putting your hand or face above the mug.

As you're heating the temperature of the water will rise at different rates, depending on the amount of heat, on the quantity of water, and on whether the pan is covered or not. With the tea in the pan, this would create an infusion gradient, as the temperature rose over a varying number of minutes.

If you boil the water first, then infuse, you've fewer variables: the quantity of tea and the quantity of water. So you'll have less to adjust to get the brew perfect.

I don't see how you could brew even the finest black tea for 10-20 minutes without over-extracting it, producing a stewed, bitter flavour that dries the tongue.