• Preheat the oven to 425°F. Line a large baking sheet with parchment and spray it lightly with cooking oil.
• In a small bowl, stir together the marinara and tomato paste until smooth.
• Set a wonton wrapper on a clean, dry surface. Spoon about a teaspoon of the sauce into the center, top with a little crumbled feta, then about a teaspoon of sausage. Keep the pile small so it seals.
• Dab the edges of the wrapper with a wet finger. Fold two opposite corners over the filling so they overlap like a hug, then fold the remaining two corners into the center to make a rectangle. Press the seams with a wet fingertip to seal. Set on the baking sheet and repeat with the rest.
  
• Spray the tops lightly with cooking oil or brush with a little olive oil. Bake for 12 to 15 minutes, until golden brown and bubbling.
• Let them rest on a rack for about 3 minutes so the filling settles, then transfer to a tray with a spatula and serve warm.

To Air Fry

• Assemble the wontons through folding and sealing (steps 2 to 4 above). Preheat the air fryer to 375°F.
• Spray or brush both sides of the wontons lightly with oil. Arrange in a single layer in the basket without crowding, working in batches as needed.
• Air fry for 7 to 9 minutes, until golden brown and crisp, shaking or flipping halfway. Let rest a couple of minutes, then serve warm.