Pat scallops dry with paper towels. Heat oil in a large nonstick skillet over medium-high heat. Add scallops to pan, and cook 3 minutes on each side or until browned. Remove from pan, set aside, and keep warm.
Reduce heat to medium; add shallots, mushrooms, salt, and pepper to pan, and sauté 3 minutes. Stir in garlic and tomato paste; cook 1 minute, stirring often. Add tomatoes and thyme. Reduce heat to low, and simmer 6 minutes, stirring often.
Return scallops to pan, and cook 2 to 3 minutes or until thoroughly heated. Stir in basil and lemon juice.