Spicy Avocado Dill Dip

1 medium ripe avocado

1 cup sour cream

1/4 cup chopped fresh dill, plus a few sprigs for garnish

2 scallions, white and green parts, thinly sliced

1 clove garlic, minced

1/2 medium jalapeno, minced, seeded for milder heat

1/2 teaspoon kosher salt

1/4 teaspoon cracked black pepper