Chicory Salad with Roast Beef and Fennel

Slice the fennel into wafer-thin slices and save the fronds. Quarter the radishes and dice the apple. Halve the chicory lengthwise, remove the hard core, and separate the leaves. Crush the mustard seeds and mix with pressed garlic, apple cider vinegar, lemon zest, pepper, and salt to make a dressing. Combine the chicory, fennel, apple, and radishes with the dressing. Arrange on a plate, roll up the roast beef slices, and distribute them over the salad. Garnish with fennel fronds.