Break or chop mushrooms into 1/4-inch pieces and cover with 1/4 cup warm water. Let sit for 30 minutes to rehydrate. Strain mushrooms, reserving soaking liquid in a small bowl. Rinse mushrooms and set aside. Strain soaking liquid through a paper towel into a small pot and reduce by half over medium heat.
Combine hazelnut oil, walnut oil and olive oil in a small bowl. Combine vinegar, shallot, chives and salt and pepper in a separate medium mixing bowl and whisk in warm soaking liquid. Continue whisking and add oil in a slow thin stream to emulsify.
Lay out slices of tomato. Top with salad greens and mushrooms. Drizzle with warm dressing and top with 2 small romaine leaves.