Rub lemons with 2 teaspoons oil; place in a greased 9-in. square baking dish. Bake, uncovered, at 425° for 15-20 minutes or until tender.
Meanwhile, in a large bowl, combine the salad greens, pea shoots and radishes.
Cool lemons slightly. Squeeze juice into a small bowl. Finely grate 1/2 teaspoon lemon peel; add to the bowl. Whisk in the sugar, mustard, salt, pepper and remaining oil. Drizzle over salad; toss to coat.