Heat oven to 350 degrees F. Spray a mini muffin tin with cooking spray, then press 1 wonton wrapper into each cup, folding the corners back to leave the center nice and open for the filling.
Bake until lightly browned, 8 to 10 minutes. Allow to cool for at least a few minutes before removing and filling.
Line a large baking sheet with foil or parchment paper. Combine the olive oil, shrimp, lime juice, chili powder, salt and pepper in a bowl and toss to coat. Spread shrimp out in a single layer on the prepared baking sheet. Bake for 8-12 minutes or until opaque and cooked through. Remove and allow to cool slightly. (I am able to fit these in with the wonton cups, but if done separately, just leave the oven at 350 when the wonton cups are done and bake at that temp for the stated time.)
While the shrimp and/or wonton cups are baking, combine the sour cream and lime juice in a small bowl. Season with salt and pepper, to taste, and set aside.
To assemble, place a few arugula leaves in the bottom of each cup, top with a spoonful of lime sour cream and then 2 or 3 of the chili lime shrimp, depending on their size. Serve with additional lime wedges, for squeezing on top, if desired.