Coffee for a moka pot
The moka pot is the most common coffee maker in Spanish homes and the one with the worst reputation, nearly always because of two habits that have nothing to do with the coffee you use.
Which grind it needs
Fine, but slightly coarser than for espresso. A moka works at 1.5-2 bar, far from espresso's 9, so an espresso grind clogs it and over-extracts.
If you buy ground, ask for it specified for a moka pot. A generic grind doesn't suit any particular machine.
Which roast to choose
Medium and medium-dark roasts. A moka concentrates fairly heavily — around 5% dissolved solids — and emphasises body, so chocolate, nut and caramel profiles work better than very acidic ones.
Very dark roasts, and especially supermarket torrefacto, turn sharply bitter in this method precisely because of that concentration.
The two mistakes that make it bitter
1 · Filling the base with cold water. It drags out the heating and the coffee stews before extracting. Use hot water and you'll notice the difference from day one.
2 · Tamping the coffee in the funnel. Never tamp. Fill level and smooth with a finger, without pressing.
And a minor third: take it off the heat as soon as it starts gurgling, rather than waiting for everything to come through.
Freshly roasted in Almería and shipped within 24-72 hours.