How to Make It
In a large saucepan of boiling water, cook the rice over moderately high heat, stirring occasionally, until tender, about 12 minutes. Drain and spread on a baking sheet to cool.
In a large skillet, toast the Old Bay Seasoning over low heat until fragrant, about 40 seconds. Scrape the spice mixture into a small bowl and let cool. Melt the butter in the skillet. Add the crabmeat and 1 teaspoon of the Old Bay Seasoning and cook over moderately high heat for 1 1/2 minutes, tossing gently with a spatula. Transfer to a plate.
Heat the oil in the skillet. Add the onion and cook over moderately low heat until softened, about 4 minutes. Add the garlic and the remaining 2 teaspoons of Old Bay and cook, stirring, until fragrant, about 2 minutes. Add the tomatoes and cook until dry, about 4 minutes. Add the rice and cook over moderate heat, stirring, until heated through, about 3 minutes. Add the crabmeat and lemon juice and cook, stirring, until hot. Season with salt and transfer to warmed bowls. Sprinkle the scallions over the rice and serve.