Because there is only one flat-iron steak per steer, it's a good idea to call ahead and order two steaks. Flank or tri-tip steaks make fine substitutes. You'll serve roughly two-thirds of the steak for dinner Saturday night and use the rest for Sunday brunch. If you don't have a mini chopper or blender, just dice the tomatoes and parsley by hand for a chunkier sauce.
1. Combine first 6 ingredients; stir well. Rub spice mixture evenly over both sides of steaks; cover and let stand at room temperature 30 minutes.
2. Preheat grill to medium-high heat.
3. Place steaks on a grill rack coated with cooking spray; grill 3 minutes on each side or until desired degree of doneness. Remove from grill; let stand 10 minutes.
4. Place tomatoes and remaining ingredients in a mini chopper or blender; process until coarsely chopped. Spoon tomato mixture into a microwave-safe bowl; microwave on HIGH 1 minute. Cut steaks diagonally across grain into thin slices. Place 3 ounces steak on each of 4 plates (roughly 2/3 of cooked meat). (Reserve remaining steak for Sunday brunch.) Top each serving with 2 tablespoons sauce.
Wine note: Coffee flavor in food can be a fabulous pairing point for some red wines. Cabernet sauvignon and syrah often have dark espresso flavors lurking around the edges. For Saturday's supper, though, you need a red with a little more bright acidity and juicy fruit than those two varieties bring on their own. Go for a blend of syrah and its common partner grenache: Bonny Doon Vineyard's Châteauneuf-du-Pape-styled 2006 Le Cigare Volant (California, $32), with spicy, toasty, earthy notes on one side and bright red fruit on the other. --Sara Schneider