Better late than never.
For 1 1/2 pounds of flank steak
3 TBL extra virgin olive oil
3 TBL fresh lime juice
4 garlic cloves, finely chopped
1 serrano pepper, cored, seeded, then sliced or chopped
2 tsp chili powder
1 tsp ground cumin
1/2 tsp kosher salt
Mix in bowl until well blended, move to large freezer bag, add steak and massage until steak is evenly coated. Place in refriderator for at least two hours, overnight is better.
Weber Performer / 18.5 WSM / mini WSM / Primo XL / #14 Old Smokey / Weber Jumbo Joe