In a small bowl with a whisk, or in a jar with a tight-fitting lid, add the vegetable oil, red wine vinegar, sugar, dried mustard, poppy seeds, and salt to taste (I like 1 teaspoon). Stir or shake to combine. Allow the flavors to blend at room temperature while preparing the salad.
To assemble the salad:
Add butter to a small skillet over medium-high heat until the foaming subsides. Add pecans and sauté until toasted and fragrant, about 15 to 20 minutes. Remove promptly to avoid scorching and drain on paper towels. Cool 5 minutes.
In a large bowl, add spinach, strawberries, and pecans. Add salad dressing and toss until evenly coated.
You can do half baby spinach and half field greens mix if you prefer.To make the Easiest Balsamic Vinaigrette, whisk together:
1/2 cup olive oil
1/4 cup balsamic vinegar
4 teaspoons dijon mustard
Salt to taste
Toasting the pecans in butter is optional but so delicious. I definitely recommend it unless you are vegan or avoiding butter for some reason. It makes a huge difference!To toast the pecans in a dry skillet, heat a small skillet over medium-low heat. Add the pecans and toast until fragrant, about 10 to 15 minutes. Stir often to prevent scorching.