In a medium saucepan cook peas, covered, in a small amount of boiling salted water for 3 minutes. Drain and cool. Arrange peas, arugula, baby Swiss chard, and green onions in rows on a large platter or in a serving bowl.
In a screw-top jar combine Strawberry Vinegar and salad oil. Cover; shake well. Drizzle over salad. Garnish with borage flowers or other edible flowers. Store any remaining dressing in the refrigerator. Makess 8 to 10 servings.
In a medium stainless-steel or enamel saucepan combine 1 cup chopped fresh strawberries and 1 cup cider vinegar. Bring to boiling; reduce heat. Simmer, uncovered, for 3 minutes. Remove from heat. Pour the vinegar-berry mixture through a fine-mesh strainer; let the liquid drain into a bowl. Discard the berries. Transfer vinegar to a jar or bottle. Cover tightly with a nonmetallic lid (or cover with plastic wrap and tightly seal with a metal lid). Store in the refrigerator up to 6 months. Makes about 1-1/4 cups.