Zest one lemon to measure 1/2 teaspoon zest. Juice lemon to measure 2 tablespoons juice. Combine zest, juice, vinegar, sugar, oil and poppy seeds in small bowl. Whisk until well blended. Cover; refrigerate until ready to use.
Toast almonds in small pan on stove until lightly browned. Set aside to cool completely.
Place greens in large salad bowl. Add strawberries, onion, and cucumber. Whisk vinaigrette and pour over salad, tossing until evenly coated. Sprinkle with almonds and serve immediately.