1. Bring a 2-1/2-quart sauce pot of water to boil. Add salt and peas; blanch until just crisp-tender, about 1 minute. Drain in a colander and transfer peas to a bowl of ice and cold water to stop cooking. Drain and pat dry. Cut a lengthwise slit along the inside curve of each pea to create a pocket for filling. Trim lengthwise along the outside curve of pea to create a flat surface so that pea will stand up once filled. Trim radishes and halve lengthwise.
2. Whisk together cream cheese, horseradish, and ginger in a bowl; salt and pepper to taste. Stir in chopped chives. Spoon into a small heavy-duty plastic bag and snip end to form a small hole. Pipe cream cheese mixture into opening of each pea and transfer to a serving platter. Pipe cream cheese mixture in a decorative pattern on cut side of radishes. Transfer to platter and garnish with whole chives. Makes 8 servings.