4 ribs celery, cut diagonally into 1/3 slices
1/4 teaspoon celery seeds
3 tablespoon all-purpose flour
1 cup milk
Salt and pepper
1 teaspoon freshly grated lemon zest
2 teaspoons fresh lemon juice
1 1/2 pounds Brussels sprouts, trimmed, blanched for 12 minutes in boiling salted water, or until they are tender, and drained, or 2 (10-ounce) packages frozen, thawed.