Mix the cumin, chili pepper, garlic powder and salt together in a small bowl. Sprinkle half the mixture over the shrimp in a large bowl along with 1/4 cup of the tequila and 1 tablespoon of the olive oil. Toss to coat the shrimp well. Cover and refrigerate until ready to grill. Reserve the remaining spice mix.
Heat the remaining tablespoon olive oil in a pot over medium-high heat. Add the onions and peppers and cook for a few minutes until they begin to soften. Add the garlic and the remaining spice mix and cook for another minute. Add the stock, black beans, chopped tomatoes, tomato paste and 4 cups water. Bring to a boil, then reduce the heat to a simmer. Simmer, uncovered, for 45 minutes.
Mix the cornmeal or masa with a small amount of water in a bowl. Pour into the soup, then simmer for an additional 30 minutes. Check the seasonings, adding more chili powder if it needs more spice and more salt if needed. Turn off the heat, add the remaining 1/4 cup tequila and let rest for 15 to 20 minutes before serving.
Meanwhile, grill the shrimp: Heat a grill pan over medium-high heat and coat with cooking spray or brush with oil. Shake off any excess marinade and grill the shrimp until cooked through, about 2 minutes per side.
Five minutes before serving, gently stir the tortilla strips into the soup.
Ladle the soup into bowls. Top each bowl with 3 shrimp and some avocado, red onion, sour cream, cilantro leaves and lime wedges.