Prep the crab: Drain well if using canned or pasteurized. Pick through for shells. Gently flake into medium pieces so it doesn’t turn mushy.
Make the dressing: In a large bowl, whisk mayonnaise, Greek yogurt or sour cream, Dijon, lemon zest, and 1 tablespoon lemon juice.
Add Old Bay if using. The dressing should be creamy but loose enough to coat.
Add aromatics: Stir in dill, celery, red onion or shallot, and capers if using. Taste and adjust with a pinch of salt and a few grinds of pepper.
Fold in the crab: Add the crab to the bowl and gently fold with a spatula until coated.
Avoid overmixing to keep the texture intact.
Fine-tune the taste: Add more lemon juice if you want extra brightness, or a splash of olive oil for richness. Adjust salt and pepper.
Chill briefly: Cover and refrigerate for 20–30 minutes to let flavors meld. Not required, but recommended.
Serve your way: Spoon into butter lettuce cups, pile on toasted sourdough, tuck into croissants, or serve with cucumber rounds and crackers.
Garnish with a little extra dill and lemon.