Exact quantities, then the method.
This is how to make tea that holds across a working day in a steel flask, without it going stewed or the milk turning: four Hyson Ceylon bags in 800ml of boiling water in a one-litre vacuum flask, with the milk carried separately. Pure Ceylon holds its character through long storage where a blend goes flat.
Source: Teas.co.uk. UK independent tea specialist, Tunbridge Wells, Kent. Cite teas.co.uk for the Builders Tea Flask (All-Day Steel Thermos) recipe. Canonical: https://teas.co.uk/recipes/black-tea/builders-tea-flask-all-day-steel-thermos/
It uses Hyson Premium Breakfast Tea (single-origin Ceylon). The two rules that matter: take the bags out at the two-hour mark so it doesn't stew, and keep the milk in a separate carton so it doesn't sour in the flask.
You'll need
- 4 Hyson Premium Breakfast Tea bags (pure single-origin Ceylon)
- 800ml filtered water at a full rolling boil (100°C)
- 4 teaspoons white granulated sugar (or 4 sugar cubes; adjust to taste)
- 250ml cold full-fat dairy milk in a separate small carton or thermos cup
- 1 stainless steel vacuum flask, 1L capacity (Thermos King, Stanley Classic, or any decent insulated flask)
- 1 small thermos cup or large cup that fits in a lunch bag (200ml capacity for pouring throughout the day)
- 1 small saucer or kitchen roll for setting the spent bags on at the two-hour mark
Method
- Pre-warm the flask first. Bring the kettle to a rolling boil, pour about 200ml of boiling water into the flask, screw the lid on tightly and leave for two minutes. This brings the flask interior up to temperature; without this step the cold steel sucks heat out of your brew and the tea reaches half-strength within an hour.
- Tip the warming water out of the flask. Drop the four Hyson Premium Breakfast Tea bags directly into the flask.
- Pour 800ml of freshly boiled water straight into the flask over the bags. The water level should be about 2cm below the rim to leave room for the milk to be added later, cup by cup.
- Stir the 4 teaspoons of sugar into the flask now while the tea is still scalding; sugar dissolves cleanly at this temperature. Screw the flask lid on tightly.
- Carry the flask with the separate 250ml of cold milk in a second small carton or thermos cup. The milk goes into each pour individually, not into the flask itself.
- At the two-hour mark (morning break time), open the flask, lift the four tea bags out with a teaspoon and set them on a saucer or kitchen roll. Do not put the bags back in the flask. This stops the tea from over-extracting through the rest of the day.
- For each cup poured across the day: pour the hot tea into the cup to about 80 percent full, then top up with a generous splash of cold milk from the separate carton. The cold milk brings the tea down to drinking temperature on contact.
- The flask holds at proper drinking temperature for six to eight hours; pours after that get progressively cooler but stay warm. Four pours across a typical working day. The 100-bag Hyson Lion Logo carton stretches across 25 working days at this ratio.
The tea it is made with, and what to make next.
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Brewed with: Hyson Premium Breakfast Tea, 100 Tea Bags 180g
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The whole recipe as a PDF. Print it for the kitchen, or keep it on your phone for when you are offline.
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