Preheat oven to 250°. Put unpeeled eggs in a bowl of warm water. Pour 1/4 cup oil into an 8- by 8-in. pan, add kohlrabi, and turn to coat. Cover tightly with foil.
Remove eggs from water and set directly on an oven rack. Set pan of kohlrabi on another rack. Roast eggs and kohlrabi 2 hours (eggs will be freckled with brown syrupy spots). Remove eggs, crack all over under cold running water, and put in a bowl of cold water to cool.
Turn kohlrabi over in pan and cover tightly. Increase oven temperature to 375° and roast kohlrabi until butter-soft when pierced with a knife, about 1 hour. Remove foil, turn kohlrabi over, and roast until crisply browned, about 30 minutes more.
Meanwhile, in a small saucepan, heat mustard seeds over medium-high heat until just starting to pop, 2 to 3 minutes. Add 1/2 cup water, the bay leaves, vinegar, and honey. Bring to a boil, then lower heat and simmer, covered, until mustard seeds are tender, 15 to 20 minutes. Uncover and boil sauce until reduced to 1/2 cup, 2 to 5 minutes. Remove from heat and whisk in mustard. Season with salt to taste.
Peel eggs. Chop and mix with sorrel in a medium bowl.
While kohlrabi bulbs are still warm, tear some partway apart and some in half.
Spoon egg-and-sorrel mixture among 4 plates or on a big platter. Arrange kohlrabi over the mixture, drizzle with honey-and-mustard sauce, and add a few small chunks of honeycomb. Top with small sorrel leaves.
*Jeremy Fox uses red sorrel, wood sorrel, and sheep sorrel from Ubuntu's garden, but any kind of sorrel will work. Find honeycomb at well-stocked grocery stores and farmers' markets.
Quick twist: Replace the kohlrabi with small unpeeled Yukon Gold potatoes. Roast and serve them exactly the same way.
Note: Nutritional analysis is per serving.