Cut the potatoes lengthwise into 1/4-inch thick slices. Toss the potatoes in a large bowl with a couple of tablespoons of the olive oil. (The remainder of the oil will be used later.) Season potatoes lightly with salt and pepper. Lay the potatoes out in a single layer on baking sheets. Bake in the oven (350 degrees) for approximately 10-12 minutes, until tender and golden brown. Set aside to cool
Place beans and sour cream into a food processor. Pulse machine 8-10 times to lightly mash up the beans. Transfer beans to a bowl. Stir in the salmon, jalapenos, onions, olives and tortilla chips. Season to taste with salt and pepper. Set aside.
Place two large ovenproof sauté pans over high heat and add a bit of the remaining olive oil to both pans and sauté potatoes on one side until very crisp. Turn potatoes over and top each “potato nacho” with a heaping tablespoon of the salmon bean mixture. Sprinkle the cotija cheese over the top of the nachos and place sauté pans into the oven. Cook for 3-4 minutes until hot and the cheese is melted. Remove potatoes to a platter, top each with cilantro and radishes. Squeeze lime juice over the top and serve immediately.