The egg white dry-shake is central to a classic sour’s identity, but it is not the only path to a foamed surface. Concentrated aquafaba — the liquid from canned chickpeas, reduced to intensify its functional proteins — produces a foam that reads visually convincing and carries the cherry-smoke nose to the drinker’s face in the same way ovalbumin does. The chemistry is different; the experience, for most guests over the first ten minutes, is comparable.
What changes in the vegan version?
Replace the egg white with 45 mL of concentrated aquafaba. To concentrate, simmer canned chickpea liquid uncovered until the volume reduces by approximately 40%, then cool completely before use. Aquafaba’s foaming capacity comes from a saponin-protein-polysaccharide matrix that behaves like a surfactant when mechanically agitated, trapping air in a structure that superficially resembles ovalbumin foam. The critical difference is structural: ovalbumin denatures under shear and forms a tight, cross-linked protein network; aquafaba’s polysaccharide chains produce a coarser bubble lattice that begins to collapse more quickly. In practice, the foam is voluminous immediately after straining but noticeably degraded by the 10–12 minute mark.
Add approximately 0.5 g (a small pinch) of cream of tartar to the shaker before the dry shake. Cream of tartar is potassium bitartrate — an acid salt that lowers the continuous-phase pH of the aquafaba solution and slows bubble coalescence by increasing charge repulsion between foam lamellae. At this concentration, cream of tartar extends the foam’s presentable window by 2–3 minutes without affecting flavor.
What stays the same as the original recipe?
The dry-shake-first protocol still applies — shake the aquafaba, cream of tartar, and shrub without ice for a full 15–20 seconds before adding ice and shaking again. The bourbon, lemon juice, and maple syrup ratios, the cold-smoked cherry shrub, and the double-strain over a large cube are all unchanged. The only substitution is the foaming agent; every other element of the Smoked Cherry Bourbon Sour remains identical.
When is the aquafaba version the better choice?
This version is the clear call for vegan guests, anyone with an egg allergy, or service contexts where raw egg white handling creates a liability concern. It is also worth choosing in high-volume situations where sourcing pasteurized liquid egg white is inconvenient — canned chickpeas are shelf-stable and the reduction can be made in quantity and refrigerated for up to one week. Serve promptly; aquafaba foam does not hold the way ovalbumin foam does, and degradation past the 10–12 minute mark is visible.
Use the full method, equipment, and shrub measurements from the original Smoked Cherry Bourbon Sour.
