Meanwhile, halve and pit the avocados. Scoop the avocado into a medium bowl and add the lime juice, cumin, 3/4 teaspoon salt and 1/4 teaspoon pepper. Mash with a fork until combined but still a bit chunky. Add the red onions, pickled jalapenos, brine and tomatoes, reserving a few pieces of tomato and some jalapenos for garnish.