Start by heating a dry skillet over medium heat. Add the slivered almonds and toast them for about 4 minutes, stirring frequently, until they are golden brown and fragrant.

In a medium-sized jar, combine the olive oil, cider vinegar, Dijon mustard, minced garlic, and finely chopped shallot. Add in a diced strawberry, honey, and a pinch of salt. Secure the lid tightly and shake vigorously for 30 seconds until the ingredients are well emulsified.

Rinse and thoroughly dry the romaine lettuce and fresh spinach. Tear the romaine into bite-sized pieces.

In a large mixing bowl, gently combine prepared greens. Layer in crumbled feta, sliced red onion, and sliced strawberries. Sprinkle toasted almonds on top.

Drizzle the homemade vinaigrette over the salad right before serving, or keep it on the side for individual dressing preferences.