Heat olive oil in a large skillet over medium-high heat. Sear the portobello mushrooms for 3 minutes on each side until browned.
Stir together cream cheese, green pepper, and hummus until evenly blended. Season the mushroom caps with salt and pepper on each side. Place the mushrooms onto a baking sheet, with the stem-side facing up. Sprinkle with lemon pepper, then fill with hummus mixture.
Bake in preheated oven for 15 minutes until the filling is hot.