Bring a large pot of well salted water to a boil. Set up a bowl of well salted ice water. Toss the broccoli florets into the boiling water. Let the water come back to a boil and cook for 2 minutes. Immediately plunge the broccoli into the salted ice water and let it cool. Remove the cold broccoli from the ice water and reserve with the stem "coins".
In a small dry saute pan toast the coriander seeds until they become very aromatic, 3 to 4 minutes. Pulse the coriander seeds in a spice grinder to a fine powder. Reserve.
Coat a large saute pan with olive oil and add the onions. Season with salt and a pinch of crushed red pepper. Bring the pan to a medium-high heat and cook the onions until they are soft and aromatic, 7 to 8 minutes. Add the garlic, ginger, and ground coriander seed and cook for 2 to 3 more minutes. Add the tomatoes and season with salt. Bring the mix to a boil and reduce to a simmer. Simmer the mix over medium heat for about 10 minutes. Toss in the broccoli florets and the stem "coins". Cook until the tomatoes really cling to the broccoli, 10 to 12 minutes.