Heat a dry skillet over medium heat and add the walnuts. Toast for 2-3 minutes, stirring frequently until they're fragrant and lightly golden. You'll hear them start to sizzle slightly and smell that rich, nutty aroma – that's your cue they're ready.

In a small bowl, whisk together the minced garlic, Dijon mustard, and red wine vinegar until smooth. Slowly drizzle in the olive oil while whisking continuously – this creates a beautiful emulsion that coats the greens perfectly. Season with salt and pepper, tasting as you go.

Wash and thoroughly dry your mixed greens – excess water will dilute your vinaigrette and make the salad soggy. Use a salad spinner if you have one, or pat them dry with paper towels. Slice your cucumber into thin rounds, halve the cherry tomatoes to release their juices, and slice the red onion paper-thin for the best texture and mildest flavor.

Place the dried greens in a large mixing bowl. Add the cucumber slices, halved tomatoes, and red onion. Drizzle about three-quarters of the vinaigrette over the vegetables and toss gently with clean hands or salad tongs. This ensures every leaf gets coated without bruising the delicate greens.

Transfer your mixed greens salad to serving plates or a large platter. Sprinkle the crumbled goat cheese evenly across the top. Finish with the toasted walnuts for that satisfying crunch. Serve the remaining vinaigrette on the side for those who prefer extra dressing.