Use a food processor with a chopping blade to grind together the meats, the minced garlic, and the onion. Blend in the ketchup, cumin, and paprika.
Remove the meat mixture from the food processor and form by hand into round thin patties. Cook on a flat griddle or in a frying pan.
Fritas should be cooked to medium well done, but don't overcook -- they should still be nice and juicy. When the frita is just about cooked through, reduce heat to medium low, squirt on some secret sauce, and let the patties cook just a minute longer.
While the fritas are frying, use a deep fat fryer or frying pan with a couple inches of vegetable oil to fry the shoestring potatoes. Drain on paper towels and lightly salt. Keep warm.
Serve each frita on a traditional American hamburger bun.
Splash plenty of kethup spiced up with paprika on the bun and the patty.
Place the patty on the bun, cover with some sliced onion (if you like), and pile high with fresh, hot, shoe-string style fried potatoes -- yes, inside the bun, ON TOP of the meat! Splash a little ketchup on the fries, you'll be glad you did!