Heat a gas grill to high.
For the tomato-cucumber salsa: Combine the tomatoes, serrano chiles, cucumbers and onions in a medium bowl. Add the olive oil and vinegar and season with salt and pepper. Toss in the dill and mint.
For the lamb: Mix together the apricot preserves, vinegar, chipotle puree and salt and pepper in a small bowl.
Brush the lamb with canola oil and sprinkle with salt and pepper. Grill, covered, until nicely charred, 3 to 4 minutes. Flip, brush with the apricot glaze, cover and cook until a meat thermometer inserted in the thickest part reads 125 degrees F for medium rare, another 1 to 2 minutes. Transfer to a cutting board, brush with more glaze and let rest 10 minutes.
While the lamb rests, grill the tortillas for a few seconds on each side; keep warm. Slice the lamb into 1/2-inch-thick slices. Brush each tortilla with a little of the glaze, put a few slices of lamb into each, top with the salsa and serve immediately.