In large saucepan, bring 8 cups water seasoned with salt to a full rolling boil. Add pasta and bring to a boil. Cook, uncovered, for 8 to 10 minutes, or until tender but still firm, stirring occasionally. Drain, reserving 1/2 cup of the pasta water.

In large bowl, combine olive oil, lemon juice, basil, garlic, and green onions. Whisk together until blended. Add hot cooked orzo along with spinach, artichokes, roasted red pepper, and olives. Toss together until evenly mixed. Add a splash of reserved pasta water, if desired. Add salt and fresh pepper to taste.

In small bowl, combine remaining ingredients to make gremolata. Sprinkle overtop pasta with crumbled feta. Serve warm or at room temperature. Or refrigerate and serve chilled.