Preheat the oven to 425°F.
In a large bowl, stir together the prepared harissa, 1 teaspoon salt and 1/2 teaspoon pepper. Set aside.
Warm the olive oil in a large oven-proof frying pan over medium high heat. Brown the pork, turning occasionally until golden on all sides, 6 to 8 minutes total. Remove the pork from the pan.
When the pork is cool enough to handle, place it in the bowl with the harissa mixture and turn to coat. Transfer the pork back into the oven-proof frying pan, place in the oven and cook to an internal temperature of 155°F, 15 to 20 minutes. Let rest 5 to 10 minutes before slicing.
For the dipping sauce, mix the yogurt, chopped mint together, ground cumin, and lemon juice in a small bowl. Season with salt and pepper.
To serve, slice each tenderloin into 1-inch thick pieces and serve with sauce on the side.