Heat a dry skillet over medium heat and toast the slivered almonds for 3-4 minutes, stirring frequently, until fragrant and lightly golden. Transfer to a plate to cool. While the almonds toast, hull and slice the strawberries into 1/4-inch rounds, dice the avocado into 1/2-inch cubes, thinly slice the red onion, and crumble the blue cheese. I like to prep the strawberries and avocado close to serving time so they stay fresh and the avocado doesn't brown.
In a jar or small bowl, whisk together the red wine vinegar, honey, Dijon mustard, garlic powder, and poppy seeds. The mustard acts as an emulsifier, helping bind the oil and vinegar together into a cohesive dressing. Slowly drizzle in the avocado oil while whisking constantly to create an emulsion. Season with salt and pepper to taste. For a smoother dressing, I prefer using a mason jar with a tight-fitting lid—just add all ingredients and shake vigorously for 30 seconds until well combined.
Place the spinach in a large salad bowl and add the sliced strawberries, diced avocado, sliced red onion, crumbled blue cheese, and toasted almonds from Step 1. Pour the poppy seed vinaigrette from Step 2 over the salad and toss gently but thoroughly, using two large spoons or salad servers to coat all the greens and ingredients evenly without bruising the delicate spinach or avocado.
Divide the dressed salad among serving plates or bowls right away. The combination of warm almonds against cool greens and creamy avocado is best enjoyed fresh, and serving immediately prevents the spinach from wilting or the avocado from oxidizing.