In a large pan, heat oil on medium high heat until shimmery.
Add onions and pepper, cook until moderately browned- about 8 minutes.
Add shrimp and old bay seasoning, mix well.
As shrimp cooks, heat uncooked flour tortillas on a griddle pan until lightly browned and puffy, removing and setting aside in a foil pouch to keep warm as they cook.
When shrimp has cooked (about 6 minutes- shrimp will be pink and opaque), turn off heat.
Assemble tacos with beans, shrimp and fajita mixture, and top with cheese, cilantro and green onions.
