1/3 cup whole raw almonds, pulsed in a food processor or finely chopped into crumbs
Preheat the oven to 400°F.
In a large skillet, heat the oil. Sauté the shallots over high heat until brown and crispy, about 5 minutes. Remove to a bowl with a slotted spoon or spatula, leaving behind the oil.
Reduce the heat to medium. Add the leeks, garlic and ginger and sauté until soft, 3 minutes. Fold in the mustard greens (in two batches, depending on the size of the pan) and cook until wilted, about 3 minutes. In a small bowl, whisk together the cornstarch with two tablespoons water until dissolved. Add to the pan, along with the coconut milk, lime juice and salt. Simmer until slightly thickened, about 5 minutes.
If not using an ovenproof skillet, transfer the greens to a 3-quart ceramic baking dish. Sprinkle the crisped shallots and almonds over the top. Bake in the oven for 10 minutes, or until the top is lightly golden brown. Serve warm as a side dish, or over brown rice or quinoa as a vegan main course.