Cut off stems and loose outer leaves from artichoke. Cut of 1-inch from tops. Snip off sharp leaf tips. Brush cut edges with 2 t lemon juice. Place artichokes and water in a casserole. Cover with vented clear plastic wrap. Micro-cook, covered, on 100% power for 7 to 9 minutes or just till tender, rotating casserole a half-turn after 4 minutes. Let stand, covered, while preparing stuffing. For stuffing, in a small nonmetal bowl stir together carrot, onion, butter or margarine, and sage. Micro-cook, covered, on 100% power for 2 1/2 to 3 1/2 minutes or till vegetables are tender, stirring once. Stir together vegetable mixture and rice. Drain artichokes. Remove the center leaves and chokes from artichokes. Spread artichoke leaves slightly. Spoon rice stuffing into the center of each artichoke and behind each large leaf. Return artichokes to casserole. Cover with vented clear plastic warp. Micro-cook, covered, on 100% power for 2 to 3 minutes or till stuffing is hot and bases of artichokes are fork-tender, rotating the casserole a half-turn every minute. Let stand, covered, while preparing sauce. For sauce, in a 2-cup measure stir together chicken broth, 1 t lemon juice, cornstarch, and pepper. Micro-cook, uncovered, on 100% power for 2 to 3 minutes or till thickened and bubbly, stirring every 30 seconds. Stir Half the hot mixture into the egg yolk. Return all to the 2-cup measure. Micro-cook, uncovered, on 100% power for 30 seconds. Transfer stuffed artichokes to a warm serving platter. Pour sauce around the artichokes.