Heat your grill to medium high.

For the southwestern sauce:

Combine all ingredients in a bowl; add salt to taste. Stir until smooth. Refrigerate until you're ready to use.

For the grilled corn:

Place the ears of corn on the grill and cook for 2-3 minutes on each side, turning until all areas are lightly charred. Cut corn off cob. Alternatively, if you're using frozen corn kernels you can heat a small pan on the stove over high heat, add 1 teaspoon of olive oil, the corn and salt to taste. Cook, stirring occasionally until corn is charred.

For the grilled guacamole:

Cut the avocados in half, remove pits. Brush each half of the avocado with a little olive oil and place face down onto the grill. Cook for 2-3 minutes. You just want to char the exposed part of the avocado flesh, you don't want to cook it all the way through. Brush your red onion slices with olive oil and season with salt and pepper. Place your onions on the grill and cook 2-3 minutes per side or until they're soft and browned. Finely chop the grilled onion.

Scoop the avocado flesh into a medium sized bowl. Add the grilled onion, cilantro, lime juice and tomato. Add salt to taste. Mash with a fork until everything is thoroughly blended together.

Place the black bean burgers on the grill; cook for 3-5 minutes per side or until done. Add a slice of cheddar cheese on top after you've flipped them so that it has time to melt while the other side cooks.

To assemble the burgers:

Toast your hamburger buns. Place a tablespoon of southwestern sauce on the bottom bun. Add the spicy black bean burger, top with 1 tablespoon guacamole, 2 tablespoons corn and tomato slices. Place the other bun half on top and serve immediately.