Preheat oven to 425 degrees (400 convection roast).
In a medium saute pan over medium-high heat, add the olive oil. When it is hot (not smoking), add the onion, garlic, and tomatoes. Cook until onion is translucent - about 2 minutes - stirring occasionally.
Add the Mexican oregano, cumin, beer, and capers. Season with salt and pepper. Cook until liquid is reduced to only about ⅓. You need about 2-3 tablespoons of liquid for each packet.
While the beer reduces, prep the vegetables, season with a bit of sea salt and a few grinds of pepper. Toss to combine.
Rinse and pat the fish fillets dry. Season lightly with salt and pepper.
Arrange the vegetables in individual bags or packets.* Place the fish on top, and carefully spoon in half of the sauce over the fish and veggies. Seal the bag, and place on a baking sheet. Repeat with the remaining fish fillet and veggies.
Cook 10-15 minutes depending on the thickness of your fish. My 1" thick fillets needed only 10 minutes. When I've used thicker sea bass fillets, it required the full 15.
You can either serve the dish in its packet or remove the contents and plate. The bottoms of the parchment will be wet, so use a large spatula to get them out of the pan and onto the plates. Carefully cut an "X" in the top. Garnish with a lime wedge and chopped cilantro.
