Mix masa harina with water until a soft dough forms that feels like play dough. Press into tortillas. If making a design, press blue masa into the surface before cooking. Cook tortillas on a hot comal until lightly charred, then transfer to a towel-lined container and cover to steam and stay soft.
Cut halibut into strips about 4 inches long. Lightly dredge each piece in seasoned flour to help the batter adhere.
In a bowl, whisk together flour, potato starch, baking powder, salt, and paprika. Slowly pour in ice cold beer while whisking until a loose batter forms with a light, crepe-like consistency.
Spread crushed potato chips onto a tray, keeping a mix of fine and chunky pieces for texture.
Dip each piece of floured fish into the beer batter, allowing excess to drip off. Press into the crushed potato chips until fully coated.
Heat neutral oil to 350°F. Fry fish until golden brown and crispy, about 3 to 5 minutes depending on thickness. Transfer to a wire rack and season immediately with salt.
In a bowl, mix sour cream, dill, jalapeño, and garlic chive oil until smooth. Season with salt to taste. The sauce should be bright, herby, and slightly spicy.
To assemble tacos, spread green ranch sauce onto each tortilla. Add crispy fish, then top with sliced radishes, jalapeños, and fresh dill. Serve immediately.