Place a large pot of water over high heat to boil. Insert a wooden skewer through each lobster tail, lengthwise, to help them stay straight while cooking. Once the water is boiling, lower the lobster tails into the pot. Boil for 5-7 minutes, until the shells are red. Then remove with tongs and place in a large bowl of ice water to cool.
Next make the avocado slaw: Peel the avocado and place half in the blender. Add the mayo, vinegar, honey, and serrano pepper. Puree until smooth. Pour the shredded cabbage in a large bowl. Then pour the avocado puree over the top. Toss and salt to taste.
Once the lobsters are cool, use a pair of kitchen shears to cut through the shells. Roughly chop the lobster meat.
To assemble: Lay the tostada shells out flat and top with a spoonful of spicy avocado slaw. Then top with fresh mango and avocado slices, followed by pico di gallo and crumbled queso fresco. Place the chopped lobster pieces on top of each tostada and serve immediately.