Preheat oven to 400 degrees.
Toss rhubarb with brown sugar, and place on a baking sheet. Let sit for about 5 minutes while oven preheats.
Roast rhubarb for about 7 minutes or just until tender. Do not overcook or it will break down too much.
While rhubarb is roasting, make dressing: bring balsamic vinegar to a boil in a small saucepan over high heat. Reduce heat to medium and boil gently for about 5-7 minutes or until vinegar is thickened and reduced by about half. Remove from heat, and add honey and olive oil. Let cool to room temperature.
Remove cooked rhubarb from oven an let cool to room temperature.
Place spinach, strawberries, quinoa, toasted walnuts and feta in a large mixing bowl.
Add roasted rhubarb and toss to combine.
Drizzle dressing over salad and toss to combine.