Your cup should taste balanced—not sharp, not sour. There's a sweetness that comes through, and the bitterness is a background note, not a slap. If you're still getting harshness, check these:

• Are there fines in the cup? A silty bottom means your grinder is producing dust. Try shaking the grounds through a fine sieve before steeping.
• Is your water too hot? Wait a full 60 seconds after boiling.
• Are you using dark-roast beans? Dark roasts extract faster; go even coarser and drop the steep to 3 minutes.

One more thing: don't chase perfection with a blade grinder. If you're using one of those spinning-blade models, the grind is uneven by design. You'll fix over-extraction, but you'll still get a muddy cup. Consider a cheap burr grinder for travel—it's worth the weight.