Pre-heat grill and oven to 350°F.
In a small pan sweat the shallots and garlic in the butter until tender.
Remove from heat and add the lobster, parsley, chives, parmesan, breadcrumbs and lemon juice. Adjust the seasoning with lemon juice, salt and pepper.
Stuff into the caps of the portobello mushrooms to create mounds and place onto a parchment lined sheet pan.
Season the steaks with salt and pepper.
Put the steaks onto the grill. Grill the steaks to preferred doneness, for medium-rare about 3 minutes preside. Remove steaks and allow to rest while mushrooms cook.
While steaks are resting place the mushrooms into the oven and bake for 10-12 minutes until mushrooms are tender and the stuffing is starting to color.
Remove mushrooms from the oven, serve with the steaks.
Enjoy with a nice wine!