For the cabbage slaw: Add the cabbage to a mixing bowl and season with salt. Toss with your hands and gently massage the cabbage to tenderize. Add the cilantro and juice from the lime.
For the smoky chipotle aioli: Combine the mayonnaise, chipotle and agave in a small bowl. Taste and adjust the seasoning as needed.
For the Baja fish tacos: Carefully cut the halibut into 12 even-sized pieces (each about 4 inches long). Combine the cornstarch, chili powder and 3/4 cup flour in a large bowl and sprinkle with salt and pepper. Using a whisk, create a well in the center and slowly pour in the beer as you stir. Slowly incorporate the dry ingredients into the beer, forming a smooth batter.
Heat 3 inches oil in a heavy pot to 350 degrees F. Line a tray with paper towels.
Season the remaining 1/4 cup flour in a shallow dish with salt and pepper. Lightly dredge each piece of fish in it, shaking off any excess. Dip into the batter, then place in the hot oil. Cook, turning occasionally, until golden brown, 3 to 4 minutes. Drain on the paper towels and season with salt. Keep warm.
To assemble, place a large nonstick pan over medium heat. Place the tortillas in the pan 2 at a time and lightly drizzle with oil. Sprinkle with the Parmesan and cook until golden and the Parmesan is crispy and stuck to the tortilla, 30 to 40 seconds on each side.
To make each taco, smear a little chipotle aioli on the bottom of each tortilla. Top with some drained slaw, a piece of crispy fish and some Rojo Salsa. Serve with Tortilla Chips.
Remove the stems and seeds from the dried chiles, then tear them into large pieces. Toast the chiles in a large saute pan over medium-high heat until they start to change color, about 2 minutes. Remove from the heat and add hot water to just cover the chiles (about 2 cups). Place back on medium-low heat and simmer until soft and tender, 13 to 15 minutes. Remove from the heat and set aside to cool.
Preheat the broiler.
Place the tomatoes, garlic, jalapeno and onions on a baking tray, then broil until everything is charred well, turning once, 7 to 8 minutes. Transfer to a blender along with the chiles and their cooking liquid and pulse until smooth but still with a little texture. Taste and adjust the seasoning. Set aside until ready to serve.
Fresh Tortilla Chips:
Break down the salt into finer pieces in a mortar and pestle (so it sticks to the chips better).
Heat 5 to 6 inches oil to 350 degrees F in a heavy pot.
Stack up the tortillas and cut into 6 even pieces. Working in batches, sprinkle into the hot oil and cook, stirring so they don't stick together, until puffed and golden, 2 to 3 minutes. Drain and place on a rack over a tray. Season with salt immediately. Serve warm with salsa.