Slice the peel off the grapefruit, slicing deeply enough to remove the white pith as well. Working over a large bowl, cut between the membranes to release each segment, letting the segments and any juice fall into the bowl. Squeeze the grapefruit core to release any additional juice. Strain out the juice; you should have about 1/4 cup. Repeat the segmenting process with the orange.
Set the citrus segments aside. Whisk the citrus juices, olive oil, a large pinch of salt and a few grinds of fresh pepper together in another large bowl. Season to taste with more salt and pepper if needed.
Slice the tuna into strips that are about 1 1/2 inches long and 1/4 inch thick. Place the strips in a small bowl and toss with a pinch of salt and 2 teaspoons of dressing. Slice the jalapeno into thin rings, removing the seeds if desired, and roughly chop the mint.
In the large bowl with the dressing, combine the salad greens, jalapeno and mint and toss with the dressing. Transfer the mixture to a serving platter and top with the tuna and citrus segments. Shave the ricotta salata over the top. Toss, drizzle with olive oil and serve.