Recently I made the lemon meringue tart from Susan Loomis's book (which I borrowed from nice people). The crust was a bit too hard, but the lemon curd was fantastic. And the whole thing was quite pretty, too. Lemon curd may have just a couple of AOSs—think lemon meringue pie, lemon parfait—but it has lots of AOCs. Pancakes. With fruit. Made into a mousse. In a cake.
7 tbsp. butter
1 cup sugar
4 whole eggs
3/4 cup fresh lemon juice (or less, depending on how tart you want it)
zest of 1 lemon
Melt butter and sugar in the top of a double boiler. When the butter has melted, add the eggs, one at a time, and whisk well after adding each one. Add the fresh lemon juice, whisk to combine, and then cook over gentle heat (i.e., simmering water) until it has thickened, 5-10 minutes. (It took 10 minutes for me.) While it's cooking, stir frequently. When it has thickened to the consistency of not-yet-chilled pudding, or creamy yogurt, let it cool and then add the lemon zest.
If you're making a lemon meringue tart, spread it into an already-baked crust and refrigerate for a few hours. Before serving, spread meringue on top (3 egg whites and 1/3 C sugar) and broil for a minute or two.