Whisk egg, mayonnaise, dry mustard, salt, and pepper in a large bowl. Add crab, saltines and parsley. Gently fold together, just until combined. Form into 4 patties (about ¾-inch thick). Wrap patties in waxed paper and refrigerate for at least 1 hour.
Heat butter and oil in a large skillet over medium-high heat until shimmering. Add crab cakes and cook until golden and crispy, 3 to 5 minutes per side.
Serve with lemon and tartar sauce or cocktail sauce.
Notes
Add about 1 teaspoon of Old Bay seasoningto the crab mixture for some added zest and classic Maryland flavor.
Baked Crab Cakes: Pan-frying gives the patties the best flavor and a crispy, golden brown exterior. That said, you can also bake them in the oven. For baked crab cakes, preheat the oven to 450°F. Generously grease a rimmed baking sheet with butter, place patties on the pan, and brush the patties with melted butter. Bake crab cakes for 12-14 minutes, or until golden brown, flipping halfway through.
If you don't want to splurge on a container of jumbo lump crab meat, you can also use lump crab meat (which is a little bit smaller than the jumbo lump) or even backfin crab meat in a pinch. Shelf-stable canned crabmeat (near the tuna fish) and claw meat are not my preference for this recipe.
Chilling the patties for at least 1 hour (or up to 24 hours) before frying helps them stay together when they cook.
The eggs and mayonnaise act as a binder, but a filler is also important to help hold the patties together when they cook. Saltine cracker crumbs make the best filler for crab cakes. We keep the amount of breading to a minimum here, using just 5 crackers for the whole recipe. I do not recommend substituting with Panko breadcrumbs, which are flavorless and too crunchy. Instead, just put the Saltines in a little Ziploc plastic bag and crush them finely with a rolling pin or mallet. You can also process them in a mini food processor if you prefer.
Scale this recipe to feed any size crowd. If you're cooking for just two people, cut the ingredients in half and buy an 8 ounce container of crab meat. For a larger family, double all of the ingredients and cook the patties in batches.