Whisk together strawberry cream cheese and balsamic vinegar; add fresh thyme and salt. Whisk in water.
Toast pecans in a small sauté pan over medium-high heat. Remove from pan and set aside.
Melt butter in sauté pan, add onion and sauté until onion is lightly browned. Set aside to cool.
Combine spinach and onions in a large bowl. Drizzle with some of the dressing and toss. Add more dressing as needed to lightly coat spinach. Divide spinach mixture between 4 chilled plates. Top with pecans, crumbled feta cheese and strawberries. (If not doing individual plates, salad elements could be combined without dressing and served with the dressing on the side.)