Place the sliced onions in a bowl and cover with cold water. Let sit while you prepare the rest of the salad (this keeps their flavor but removes the harsh onion bite).
Make the dressing: In a bowl, whisk together all of the dressing ingrediants until well blended. Season to taste with salt + pepper. Place in the fridge until ready to use. Whisk together again right before pouring over the salad.
Place the almonds in a nonstick skillet over medium heat. Stir in the sugar and cook, stirring often, until the sugar melts and is caramelized, coating all of the almonds - about 6 to 8 minutes. Don’t take your eyes off of this as they can burn quickly!
Transfer the almonds to a piece of parchment paper to let them cool. Break them into pieces if they are clumped.
Assemble the salad: Place the spinach and basil in a large salad bowl. Add the strawberries. Drain the red onion and add to the bowl.
Drizzle about half of the dressing over the salad and toss to coat the leaves. Assess the amount of dressing. You want the spinach leaves to be nicely moistened but not swimming in dressing. Add more dressing to your desired liking.
Add the avocado, feta and candied almonds. Toss lightly to combine. Serve immediately, top each salad bowl with extra feta and candied almonds.