In a small jar, add the ingredients for the salad dressing (in no particular order) and shake well. The dressing should emulsify after 30-90 seconds of shaking. You can also mix with a whisk if you don't have a jar on hand!
Thinly slice the beefsteak tomatoes and lay them flat on a plate. Each plate should have 4-5 slices of tomato.
In a large bowl, toss the spinach, feta and pistachios. Add in the dressing and toss again.
Top the tomatoes with the salad and serve with crusty bread. Super simple but so so good.