Preparation Trim fennel stalks flush with bulb, reserving fronds and discarding stalks, and trim any discolored outer layers. Halve bulb lengthwise and discard core. Finely chop fronds and bulb. In a dry small skillet toast fennel seeds over moderate heat, shaking skillet, until fragrant and a shade darker. In an electric coffee/spice grinder grind seeds. Mince garlic and squeeze juice from lemon. In a large bowl stir together chopped fennel, ground fennel seeds, garlic, yogurt, salt, and lemon juice to taste. Tsatsiki may be made 3 days ahead and chilled, covered.
Preparation Trim fennel stalks flush with bulb, reserving fronds and discarding stalks, and trim any discolored outer layers. Halve bulb lengthwise and discard core. Finely chop fronds and bulb. In a dry small skillet toast fennel seeds over moderate heat, shaking skillet, until fragrant and a shade darker. In an electric coffee/spice grinder grind seeds. Mince garlic and squeeze juice from lemon. In a large bowl stir together chopped fennel, ground fennel seeds, garlic, yogurt, salt, and lemon juice to taste. Tsatsiki may be made 3 days ahead and chilled, covered.