Bring broth to a simmer in a medium saucepan (do not boil). Keep warm over low heat.
Melt butter in a large saucepan over medium heat; add carrot, shallot, and garlic. Cook 3 minutes or until slightly tender, stirring occasionally. Stir in saffron, and cook 30 seconds, stirring constantly. Stir in rice, and cook 2 minutes, stirring constantly. Add wine; cook until liquid is nearly absorbed, stirring constantly. Add 1/2 cup warm broth, stirring constantly until broth is nearly absorbed. Repeat with remaining broth, 1/2 cup at a time (about 25 minutes total).
Stir in tomato, and cook 1 minute, stirring often. Stir in lobster and mascarpone cheese; cook, stirring constantly, just until thoroughly heated. Remove from heat, and stir in chives and pepper. Serve immediately.
Wine note: This year, Norren Graziano helps celebrate The Trellis' 25th anniversary with chef Marcel Desaulniers and his partner, John Curtis. For this recipe, Noreen recommends 2002 Ferrari-Carano Chardonnay ($25).