Bring a saucepan of lightly salted water to a boil. Add orzo; cook 8 minutes. Drain and keep warm.

Thaw shrimp in cool water and drain. In a bowl, whisk together the lemon juice, vinegar, honey, mustard, salt and pepper. While whisking, pour in 3 tablespoons of the olive oil. Set aside.

Heat remaining 1 tablespoon olive oil in a large skillet. Add chopped red pepper and oregano; cook on medium-high heat for 3 minutes, stirring occasionally. Stir in spinach; cook an additional 2 minutes, until wilted. Stir in drained artichoke hearts, olives and thawed shrimp. Heat through. Stir in orzo and lemon juice mixture until well blended. Cook 2 minutes, then transfer to a large serving bowl. Serve warm or at room temperature.