'The Food Matters Cookbook': Mark Bittman's New Crab Cakes

1 small celery root (8 to 12 ounces), peeled and grated

1 egg

Salt and black pepper

2 tablespoons bread crumbs, preferably whole grain and homemade, or more as needed

2 tablespoons mayonnaise

1/3 cup Dijon mustard

1 small cucumber, peeled, seeded, and chopped

1 red bell pepper, chopped

1/2 cup chopped scallions

About 1 cup whole wheat flour

2 teaspoons curry powder, optional

1/4 cup vegetable oil

Lemon wedges, for serving