Slice the avocado, grapefruit, and tomatoes and set aside.

In a small frying pan over low heat, gently toss the walnuts until fragrant and toasted.

Set the walnuts aside to cool.

In a medium bowl, whisk together lemon juice, olive oil, dijon mustard, vinegar, soy sauce, and honey until creamy.

Add minced shallots, salt, and pepper, and whisk again.

Set the dressing aside until ready to mix and serve the salad.

In a large salad serving plate, layer the mixed greens and arrange grapefruit and avocado slices over it.

Scatter the halved tomatoes and toasted walnuts all over.

Drizzle the prepared dressing generously over the salad and gently toss before serving.

Serve immediately.