½ cup mayonnaise (or start with less and use just enough to hold cakes together)
2 tsp. dry mustard (or a generous tsp. prepared mustard) 
Pinch of salt
Pinch of cayenne pepper
1 celery stalk, finely minced
2 green onions, white and light green portions, finely minced
1 lb. cooked Dungeness crabmeat, picked over to remove any shell fragments
2 cups fresh bread crumbs (Panko works well also)

To make the crab cakes:

In a bowl, stir together the mayonnaise, mustard, salt and cayenne pepper. Stir in the celery and green onions. Gently fold in the crabmeat and a third to a half of the bread crumbs. Spread the remaining bread crumbs on a sheet of waxed paper. Shape the crab mixture into 8 patties, each 1 inch thick. They will only reluctantly hold together; do not overwork them. Place each cake in the bread crumbs and turn to coat evenly. Arrange the cakes on a baking sheet, cover with plastic wrap and refrigerate for 1 hour.

To cook the crab cakes:

Heat 2 large fry pans over medium heat. In each pan, melt 2 tsp. of the butter with 2 tsp. of the olive oil. Place 4 crab cakes in each pan and cook until golden brown, about 3 minutes. Turn the crab cakes over and cook until they are well browned on the other side and hot throughout, 3 to 4 minutes more.

Transfer the crab cakes to individual plates and serve immediately. Serves 4.