1. Put oven rack in middle position and preheat oven to 400 degrees F. Line a baking sheet with foil.
2. 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 puree until smooth. Add more chile if desired, processing until smooth. Transfer sauce to a bowl and chill, covered.
3. 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.
4. 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.
5. 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.

Yield: 4 servings