Common lemons (usually Eureka or Lisbon lemons) have an acidic bite. It’s this spark that brightens many sour cocktails, but sometimes that edge could use a little something extra. Meyer lemons—thought to be a cross between common lemons and mandarin oranges, and available seasonally starting in early winter—lend a milder touch to cocktails, with a heady fragrance and sweetness that meshes well with the crispness of tequila and warmth of cinnamon.