Preheat oven to 350˚F. Spread almonds on sheet tray and toast about 5 minutes, till light brown and aromatic.
Put the rice in a pot and cover with a double volume (1 1/2 cups) of reserved poaching liquid. Bring to a boil, reduce heat, cover and cook for 25 minutes (45 for brown rice). Turn off heat and let rest at least 5 minutes before serving.
Pat sweetbreads dry with a paper towel and cut or break into pieces of the desired size and shape. Dredge in cornstarch and tap to remove excess.
Heat oil in a skillet or frying pan over medium high heat until shimmering, and then sear sweetbreads, turning, until evenly browned. Reserve and drain all but 1 tablespoon oil.
Add onions, garlic, and ginger to pan and sauté until they start to turn translucent.
Add sherry to pan and reduce by half. Add soy, vinegar, honey and poaching liquid, and bring to a simmer. Add sweetbreads and cook until slightly thickened, about 5 minutes. Make sure the sweetbreads are evenly and generously coated with the glaze and remove from the pan.
Add mustard greens, and if necessary, a little water to the pan and cook just until wilted.
To serve, spoon the greens over the rice, and top with sweetbreads and toasted almonds.