01 - Melt butter in a nonstick skillet over medium heat. Add walnuts and sugar, stirring constantly until sugar melts and evenly coats the nuts, approximately 3–4 minutes. Transfer walnuts to parchment paper, separating into individual pieces to cool completely.
02 - Combine olive oil, balsamic vinegar, Dijon mustard, honey, salt, and pepper in a small bowl or jar. Whisk vigorously until fully emulsified, or shake jar until dressing thickens and ingredients are thoroughly incorporated.
03 - Place baby spinach in a large serving bowl. Arrange sliced strawberries, red onion, and crumbled goat cheese evenly over the greens.
04 - Sprinkle cooled candied walnuts across the top of the salad, distributing evenly for consistent crunch in each serving.
05 - Drizzle balsamic vinaigrette over salad immediately before serving. Toss gently to coat all ingredients without damaging delicate spinach leaves. Serve promptly to maintain crisp texture.