Spanakopita: Difficult to spell, but delicious to taste. We've based this tart on the Grecian classic, with flaky, golden puff pastry filled with a creamy, rich combination of feta, ricotta, and spinach. A perfectly pungent salad with a dressing of red wine vinegar and oregano pairs perfectly with the tart. Απολαμβάνω! (Now that's difficult to spell!)
Halve and peel onion. Slice half the onion into thin strips and cut other half into ¼" dice. Coarsely chop spinach. Core tomato and cut into ¼" rounds. Quarter rounds into wedges. Trim cucumber, peel, and cut into ¼" half-moons. Stem and mince oregano. Mix cornstarch and ¼ cup water in a large mixing bowl.
Cook the Spinach Filling
Heat a large non-stick pan over medium-high heat. Add 2 tsp. olive oil and diced onion to hot pan, and cook until softened, 2-3 minutes. Add spinach and cook until wilted, 2-3 minutes. Stir in cornstarch slurry. Remove from burner and transfer spinach filling to mixing bowl used for slurry. Season with ¼ tsp. salt. Let filling rest until it is cool to the touch. While filling cools, marinate vegetables.
Marinate the Vegetables
In another mixing bowl, combine red wine vinegar, 2 tsp. olive oil, half the oregano (reserve remaining for filling), ¼ tsp. salt, and pinch of pepper. Toss in tomato, cucumber, and sliced onion. Set aside to marinate. While vegetables marinate, finish spinach filling.
Finish the Spinach Filling
Once spinach filling has cooled to the touch, add ricotta, feta, remaining oregano, and ¼ tsp. salt to bowl. Mix thoroughly.
Assemble the Tart
Remove any paper in between sheets of puff pastry. Place one puff pastry square onto prepared baking sheet. Scoop spinach filling onto dough center, leaving ¼" border. Lightly brush dough border with water. Gently stretch second puff pastry square ¼" in each direction, and cut a vent in the middle. Place dough square over filling, meeting first dough square. Use a fork to crimp and press dough pieces together. Brush top with 1 tsp. olive oil.
Finish the Dish
Bake until tart is puffed up and browned, 16-20 minutes. Remove from oven and rest 3-5 minutes. Quarter tart and place two quarters on a plate. Place salad next to tart.