Japanese bread crumbs, called panko , give these cakes a light, crisp coating. Panko is sold at Asian markets and can often be found in the seafood section of large supermarkets. But if it’s unavailable, plain dry bread crumbs are an acceptable substitute.

For sauce
1/2 ripe medium California avocado, pitted and peeled
1 tablespoon low-fat mayonnaise
1 tablespoon fresh lime juice
1/4 teaspoon salt
1/4 teaspoon sugar
1 fresh jalapeño or serrano chile (including seeds), stemmed and quartered lengthwise
1/4 cup fat-free (skim) milk

For crab cakes
1 pound jumbo lump crabmeat, picked over and coarsely shredded
3 tablespoons low-fat mayonnaise
1/4 cup minced fresh chives
1 tablespoon fresh lemon juice
1 teaspoon Dijon mustard
1/4 teaspoon black pepper
1/2 cup panko (Japanese bread crumbs)
1 tablespoon unsalted butter
2 garlic cloves, smashed
1/2 teaspoon herbes de Provence or 1/4 teaspoon dried thyme
1/4 teaspoon salt

Put oven rack in middle position and preheat oven to 400°F. Line a baking sheet with foil.

Make sauce:
Pulse avocado with mayonnaise, lime juice, salt, sugar, and one fourth of chile in a food processor until chile is finely chopped. Add milk and purée until smooth. Add more chile if desired, processing until smooth. Transfer sauce to a bowl and chill, covered.

Make crab cakes:
Stir together crabmeat, mayonnaise, chives, lemon juice, mustard, pepper, and 1 tablespoon panko in a large bowl until blended well, then chill, covered.

Melt butter in a medium nonstick skillet over moderate heat, then cook garlic, stirring, until golden and fragrant, about 2 minutes. Add herbes de Provence, salt, and remaining 7 tablespoons panko and cook, stirring, until golden brown, about 6 minutes. Transfer crumbs to a plate to cool. Discard garlic.

Divide crabmeat mixture into 4 mounds on a sheet of wax paper. Form 1 mound into a patty, then carefully turn patty in crumb mixture to coat top and bottom. Transfer to a baking sheet and repeat with remaining 3 mounds, then sprinkle remaining crumbs on top of crab cakes. Bake until heated through, about 15 minutes. Serve crab cakes with sauce.