It’s no surprise that tofu brings protein to the party, but artichokes are also a good source, boasting one gram of protein per heart.
Preheat oven to 450°F with rack positioned 8 inches from heat source. Cut tofu into 3/4-inch cubes; pat with paper towels until very dry. Pat artichokes with paper towels until very dry.
Arrange tofu and artichokes on a rimmed baking sheet. Drizzle with 3 tablespoons of the oil; stir gently to coat. Sprinkle with pepper and 1/4 teaspoon of the salt. Roast in preheated oven 10 minutes. Increase oven temperature to broil (leaving baking sheet in oven); broil until mixture is golden brown, 5 to 8 minutes. Remove from oven.
While tofu and artichokes roast, remove and discard fennel stalks, reserving fronds. Chop fronds to measure 2 tablespoons. Core and thinly slice fennel bulb lengthwise to measure 3/4 cup. (Reserve remaining fronds and bulb for another use.)
Slice off top and bottom of grapefruit. Standing it on one end, slice off peel and white pith. Working over a bowl to catch the juice, slice segments from the membrane. Set segments aside. Squeeze additional juice from grapefruit into bowl, if needed, to measure 3 tablespoons total.
Add honey and remaining 3 tablespoons oil and 1/4 teaspoon salt to grapefruit juice in bowl; whisk until combined.
Arrange tofu, artichokes, and radicchio on a large platter. Top with sliced fennel, orange rounds, and grapefruit segments. Drizzle with dressing; sprinkle with fennel fronds, pine nuts, and chives.