Bring a large pot of water to a rolling boil over high heat and plunge the corn into it. Cover, and when the corn returns to a boil, turn off the heat. Let the corn sit for 5 minutes.
Using tongs, lift out the corn and rinse with cold water to cool. Scrape the kernels off the cob, and put them into the work bowl of a food processor. Add the eggs and flour, and process in short pulses until the mixture is still coarse in texture but even in color and well-combined. Stir in the sugar, cumin if making plain corn cakes, and salt.
Rub a little olive oil over the surface of a heavy nonstick pan or griddle, and heat until a bit of batter dropped on the surface bubbles in the center and browns on the bottom.
If making plain corn cakes, pour 3 tablespoons of batter into the pan or onto the griddle. When bubbles form on the surface and the bottom has browned, about 3 to 4 minutes, flip it over (using a nonmetallic spatula) to brown the other side, about 3 to 4 minutes more. Transfer to a warm plate and cover with foil to keep warm, and repeat until you've used up all the batter. Serve each corncake spread with one of the pestos and/or garnished with sour cream, yogurt cheese, and salsa, if you'd like.
If making crab-filled corncakes, pour 3 tablespoons of batter into the pan or onto the griddle, and when bubbles form on the side and the bottom is lightly browned, about 4 minutes, place a generous spoonful of Crab Filling in the center.
Cover the filling with another 3 tablespoons of corn batter. Using a nonmetallic spatula, carefully flip the corncake to cook the other side until brown, about another 4 minutes. Transfer the corncake to a plate and cover with foil to keep warm. Serve the crab cakes garnished with sour cream, yogurt cheese, alfalfa sprouts, cherry tomatoes, and/or slivers of ripe avocado.
Combine all of the ingredients in the bowl of a food processor or blender. Process to make a smooth, dense paste.
In a food processor or blender, make a dense paste by blending the broccoli, Parmesan, and Cheddar. Add the mace and process again to distribute it throughout the pesto.
In a bowl, combine the mayonnaise, scallion, capers, chives, and crabmeat. Stir well with a fork to blend the ingredients evenly. Refrigerate until ready to use.