Do I need an ice cream maker?
No, but it helps. An ice cream maker whips in a little air and breaks up ice crystals as it freezes, which is how you get that smooth sorbet texture. If you don't have one, use the no-churn method in the instructions. It takes a little more hands-on time, but it works.
Why is my sorbet icy?
Usually one of three things: (1) not enough sugar, (2) the base wasn't fully chilled before freezing, or (3) it was stored uncovered or poorly sealed and picked up freezer air. Make sure you dissolve all the sugar, chill the base thoroughly, and store it with parchment pressed on top. If it's already icy, let it soften in the fridge, stir vigorously, then re-freeze. It'll improve, even if it won't become perfect.
Can I use bottled lemon juice?
You can, but the flavor will be flatter and sometimes slightly metallic. Fresh juice is kind of the whole point here. If you must use bottled, adding extra zest can help boost the aroma, but it won't fully mimic fresh lemons.
How do I keep it from tasting bitter?
Zest only the yellow part. The white pith is where bitterness lives. Also, don't boil the zest aggressively for a long time. A quick steep in warm syrup is enough.
Can I make it less tart?
Yes. Add 2 to 4 more tablespoons of sugar, or serve with berries, shortbread, or a dollop of whipped cream to mellow it out. You can also reduce lemon juice by 2 tablespoons and replace with water.
Is lemon sorbet dairy-free and gluten-free?
Yep, as written it's dairy-free and gluten-free.