Stir together first 3 ingredients. Cover and chill up to 3 days.
Sauté bell pepper and onions in hot oil in a small nonstick skillet over medium-high heat 1 minute; add garlic, and sauté 1 minute. Remove from heat; cool 15 minutes.
Combine bell pepper mixture, mayonnaise, and next 5 ingredients in a large bowl. Fold in cornbread and crabmeat. Shape mixture into 16 (2 1/2-inch) cakes (about 1/4 cup each); place on a lightly greased baking sheet. Cover loosely with plastic wrap, and chill 1 hour.
Lightly coat cakes with cooking spray. Cook crab cakes, in batches, in a large nonstick skillet or griddle over medium heat 3 to 4 minutes on each side or until lightly browned. Serve immediately with cilantro-jalapeño sour cream.