To remove the lobster meat from the shell, use kitchen shears to cut a lengthwise incision up the middle of the top and underside of the shell. Pull the shell apart and remove the tail meat.
Heat the oil in a large, heavy, shallow skillet over medium-high heat. Add the butter and melt until foamy.
Sprinkle the lobster meat with the garlic salt and pepper. Panfry the lobster in the butter and oil until golden and cooked through, about 8 minutes. Transfer to plate and cover with aluminum foil to keep warm.
Place a warm flour tortilla on a work surface. Spread 3 tablespoons warm refried beans, then top with 1/4 cup Arroz Rojo and finish with about 2 ounces cooked lobster meat. Fold in the sides of the tortilla over the filling and roll up to completely enclose. Serve hot with salsa, if desired.
Using a box grater, grate the tomato into a medium bowl, discarding the tomato skin.
Heat the oil in a medium heavy skillet over medium-high heat. Add the onions and saute until translucent, about 5 minutes. Add the garlic and cook for 1 minute. Stir in the rice and cook until slightly toasted, about 3 minutes.
Add the broth, tomato sauce and grated tomato and bring to a boil. Add the serrano, cilantro sprig and salt, to taste. Bring to a boil, reduce the heat to medium and simmer until the liquid is absorbed and the rice is tender, about 15 minutes.
Turn off the heat under the skillet. Cover the rice and let stand for 8 minutes. Fluff the rice with a fork, transfer to a serving bowl and serve.