1. Wash spinach by filling a large bowl or sink with water and covering the leaves for 5 minutes. In an even layer, place leaves on a bed of paper towels or strain with a salad spinner. Set aside.
2. Cut the ends off and peel a small white onion. Cut the onion in half and slice each half into thin strips.
3. Place the onion in a pan over medium heat with the water and stir every 3-5 minutes for 12 minutes. Onions will begin to caramelize.
4. While onions cook, add balsamic vinegar and rice wine vinegar to a medium-sized bowl and whisk in the olive oil until well mixed. Season with the salt and pepper.
5. Stir onions and turn off heat before slicing the spinach into ribbons and adding it to the dressing. This helps to break down the spinach and is easier to eat. Toss the spinach with a gloved hand or tongs until evenly coated.
6. Thinly slice strawberries and toss with the spinach. Plate the mixture and add 1/4 of the onions to each plate and add a tablespoon of chopped pecans to each plate. Add 1/2 tbsp. of goat cheese to each plate if preferred.