Step 1

Heat oil in a 4 to 5 quart Dutch oven or stockpot over medium until the oil shimmers. Add the onions and cook until softened, about 5 minutes. Add the garlic and cilantro stems and stir until fragrant. Sprinkle in the turmeric and curry powder and mix with the onions until all is colored yellow with the spices. Add a splash of stock and stir to make sure the spice powders have dissolved.

Step 2

Pour in the rest of the stock, the coconut milk, and the broccoli and cauliflower, plus 1 teaspoon of salt. Increase heat to high and bring just to a boil, then reduce heat to medium-low to maintain a gentle simmer. Cover partially with a lid or a piece of foil, and cook 15 to 20 minutes, until the vegetables are tender enough to be pierced with the tip of a knife. The broccoli should still be bright green (not the olive drab it turns when over cooked). Turn heat to low.

Step 3

Transfer soup to blender, and add the mustard, herbs, a big pinch of salt, and a grind of pepper. Purée until completely smooth* - the herbs and broccoli should be reduced to flecks. (If necessary, process the soup in batches, adding the mustard and herbs to the first batch. Return all of the soup to the pot and taste. Add a squeeze of lemon juice, a pinch of salt, and taste again. Repeat, adding more lemon juice and salt until seasoned properly (I find it takes about 2 tablespoons of lemon juice and 1/2 teaspoon salt to reach my liking). Before serving, add a grind of black pepper.