Try this Tartar Sauce I recipe
Standard mayonnaise differs from hollandaise because it relies on cold emulsification rather than heat-set proteins. This cold preparation creates a semi-solid matrix of oil droplets suspended in water, stabilized by lecithin from egg yolks. When combining mayonnaise with sweet pickle relish and minced onion for tartar sauce, you introduce moisture from the vegetables. Mincing the onion finely prevents large aqueous pockets from destabilizing the delicate fat suspension.
Allowing the mixture to rest in the refrigerator for at least sixty minutes is chemically necessary. This chilling window permits the soluble aromatics from the onion and the organic acids from the lemon juice to partition evenly throughout the lipid phase. Serving the condiment immediately results in sharp, isolated pockets of acidity rather than a cohesive flavor profile.
Never attempt to freeze this emulsion. Freezing causes water molecules to expand into jagged ice crystals, which mechanically rupture the protective protein films surrounding the oil droplets. Upon thawing, the emulsion breaks completely, releasing pools of separated oil and rendering the condiment grainy and watery. Keep the sauce strictly refrigerated at or below 40 degrees Fahrenheit.
Store prepared sauce in an airtight glass jar for up to five days. Glass prevents flavor transfer from the refrigerator air into the delicate fats. If the condiment separates during storage due to minor temperature fluctuations, whisking vigorously by hand can sometimes reincorporate small amounts of free oil, though severe separation requires discarding the batch.