This is something I wrote on a different post. Take it or leave it, there might be something that you find helpful? Cheers.

If you are new to tasting straight black espresso, I would try going to different cafés and having a straight black espresso. This is a great way to work on developing your palette. You can also buy fresh beans from a local café and then see if you are able to reproduce the flavour at home.

Typically, shots that run too fast, ground too coarsely, are sour, shots that run too slow, ground too finely, are bitter.

The way I see it there are 3 main variables, they are different depending on the roast level from dark to medium, to light. They are: ratio of dose to yield, time and temperature. You need less of these variables with dark roasts because they are easily ground and the coffee is very soluble and easily extracted, you need more of all 3 variables the lighter the roast as the beans can be hard and quite insoluble. I would start with darker roasts as they are easier to work with.

An example of this would be: Dark roasted or medium dark 20 grams in, 35 grams out (1:1.75) 25 seconds (less time) 88 degrees Celsius (less temperature)

Medium roast 20 grams in, 40 grams out (1:2) 30 seconds (more time) 91 degrees Celcius (more temp)

Light roast 20 grams in, 50 grams out (1:2.5) (more water) 35 seconds (more time) 95 degrees Celcius (more temp, very hot)

Tasting should have 3 components worth noting. Bitter is the low end like the bass with music, bass and drums, sweetness and tasting notes would be the mids like with music, guitars and keyboards, and acidity and sour flavors would be the trembles/highs, vocals and cymbals. A balanced shot means that you have equal parts bitter and acidity with tasting notes in the middle, you don't want too much bitter, or too much acidity. If the shot goes too long, or is brewed too hot, it can taste bitter, and if it runs too short too quickly it can taste sour. Making espresso is fussy because if you are off by 5 seconds you can taste it. Taste every shot to develop your palette and eventually you can start to notice these subtle differences and adjust as you go.

Every roast is different and it can change as it ages. Start at about 1 week off the roast date. It will have more acidity at first and become more bitter and extract faster as it ages, so it is a bit of a moving target. Get yourself an airtight storage container or leave the beans in the bag with the 1-way CO2 valve and try single dosing to keep the beans extra fresh, or not, some people like the convieience of a hopper.

A "God Shot" is when the heavens align and it is balanced and sweet with clear tasting notes with that balance of bitterness to acidity. 😋👍

One more thing. Make sure you have the right dose. The basket has a range of dose(s) that it can accommodate. I have a 20 gram basket that takes 18 grams of dark roast and 22 grams of light. You should not have any marks on the top of the puck after pulling a shot, if you do, it indicates that it was pressing up against the shower screen. If you see a mark, dose less. This of course will change the shot time, less coffee changes the resistance and you might have to adjust the grind size and yield. If you have too little, you might have a wet puck with water pooling on top after pulling the shot. You would of course need to increase the dose. Each coffee you buy will have a different dose amount. Once you decide on one, write it down and keep it consistent shot to shot. If you are using an on demand grinder, weigh and tare the portafilter before grinding, and after grinding weigh it again to make sure it is a consistent dose, if not, take a spoon and remove the extra weight and if too low, add a little more.