2 cups fresh raspberries
1/3 cup sugar
1/3 cup vegetable oil
2 tablespoons white wine vinegar or cider vinegar
1/4 teaspoon Worcestershire sauce
1 (6 ounce) package fresh baby spinach
1 small red onion, thinly sliced, pulled into rings
1/2 cup crumbled feta cheese
1/2 cup chopped walnuts
In a saucepan over medium heat, bring raspberries and sugar to a boil. Cook for 1 minute. Strain and discard pulp. In a blender, combine the raspberry juice, oil, vinegar and Worcestershire sauce if desired; covered and process until smooth.
In a salad bowl, combine the spinach, onion, cheese and walnuts. Drizzle with desired amount of dressing; toss to coat. Refrigerate any remaining dressing.