Combine grapefruit juice, roasted garlic, olive oil and zest in a blender. Season with salt and pepper. Puree; this is the mojo.
Combine red onions, jicama, and grapefruit segments and dress with the mojo. Taste and adjust the seasonings. Set aside.
In a saute pan, heat a little oil over high heat. Season scallops with salt and pepper. When the oil is smoking, sear the scallops on both sides, remove from the pan, and set aside.
Deglaze the saute pan with balsamic vinegar, then add Worcestershire and panela. Cook until thick and syrupy. Add scallops back to the pan and pour over jicama and grapefruit salsa.
Divide the scallops and salsa onto 4 plates.