It’s hard to get a bad coffee these days.
Plenty of baristas have fine-tuned the process of making espresso, but really there are only a handful of variables they can control:
1. Coarseness of the grind
2. Temperature of the extraction
3. Extraction time
4. The all-important coffee-to-water ratio
Coffee roasters and barista schools have produced many impressively complex charts plotting grams of coffee against volume of water overlaid with concentration and yield.
In the middle is the ideal weight/ volume/ concentration yield target for the perfect cup of coffee.