Gather lump crab meat in a paper towel and squeeze out excess moisture. Place lump crab meat in a mixing bowl with mayonnaise, Panko bread crumbs and green onion.
Sauté red bell pepper, celery and garlic in 1/2 tbsp. butter over medium high heat for about 1 minute, until just softened. Remove from heat and let cool, then add to lump crab mixture. Season with salt and pepper.
Gently combine ingredients, making sure not to over mix. You want the lump crab to remain in lump form. When combined, form into 4 even patties. Place on a plate, cover with saran wrap and refrigerate at least an hour, preferably overnight.
When ready to cook, pre-heat oven to 350 degrees. Remove crab cakes from refrigerator and let rest while you heat your sauté pan to medium high. Add avocado oil to pan and let warm. Place crab cakes in pan and brown for about 2 1/2 minutes on each side, adding remaining 1 tbsp. butter to pan after flipping to second side. Remove from sauté pan, place on sheet pan and bake in oven for about 5 minutes while you make serrano cream and garnish.