Ginger Lime Cauliflower

Name: Ginger-Lime Cauliflower
Ingredients: ½ tsp. kosher salt plus more; 1 2” piece ginger, peeled; ½ medium head cauliflower, cut into small florets; 1 Tbsp. olive oil; 1 tsp. yellow mustard seeds; 1 tsp. fennel seeds; 1 tsp. ground coriander; 1 tsp. ground cumin; 1 tsp. ground turmeric; ¼ cup fresh lime juice; Cilantro leaves with tender stems (for serving)