Marinate the pork overnight in the wine, balsamic vinegar, and garlic.
Preheat the grill on high. When hot, brush the pork tenderloins with olive oil and sear each side for about a minute. Lower the heat to medium and cook, covered, for 8 to 10 minutes per side, brushing generously with the guava barbeque sauce at least twice.
Remove the pork tenderloins from the heat, glaze with another thick coat of the barbeque sauce, and let rest on a plate for at least 5 minutes. Then slice the tenderloins into 1-inch medallions. The pork should be served warm with a side of papaya salsa.
In a small saucepan, combine all the sauce ingredients. Simmer over low heat, stirring occasionally with a wooden spoon until the guava paste dissolves and the ingredients combine to form a thick, syrupy sauce, 15 to 20 minutes. Cool to room temperature. If not using immediately, refrigerate.
Combine all the ingredients together in a medium bowl. Toss, cover, and refrigerate until ready to serve. Bring to room temperature before serving.