How to Make It
Combine first 6 ingredients and 1 teaspoon lemon juice in a food processor; pulse until coarsely pureed. Add olive oil, and pulse to combine.
Combine tuna and artichoke hearts in a medium bowl. Stir in ground black pepper and remaining lemon juice; toss well.
Cut baguettes in half lengthwise; tear out about two-thirds of the soft interior. (Reserve removed bread for another use.) Divide tuna mixture, olive mixture, tomato slices, egg slices, and fennel evenly among baguettes. Sprinkle with coarse black pepper, if desired.
Wrap sandwiches in plastic wrap, and place on a baking sheet. Cover with a second baking sheet, and weigh down with canned goods or other heavy items. Chill 4 hours, turning once. Serve at room temperature.