Place whole jalapeños on a foil-lined, mini baking sheet. Broil for 10 minutes. Flip and broil for an additional 5 minutes. Immediately place in a zip-lock bag and let "steam" for about 5 minutes.
Remove jalapeños from bag and skin should peel off easily. Once skin is remove, cut and de-seed. Dice roasted jalapeños and then smash with your knife.