Cook bacon in a large skillet until crisp; drain well, reserving bacon drippings in skillet. Set bacon aside.
Sauté onion rings in reserved drippings until tender. Remove skillet from heat; set aside.
Combine flour and spices in a shallow pan. Carefully rinse shad roe, and sprinkle with lemon juice; dredge in flour mixture. Place roe in skillet with sautéed onion. Cover and cook over medium-high heat 5 minutes or until roe is no longer red. Transfer roe to individual serving plates. Arrange bacon and onion slices over top. Serve hot.