Heat an oven to 500 degrees F (260 C) and line a baking sheet with foil (avoid parchment paper, which will burn and disintegrate at higher temps). Roast for about 20 minutes, or until nearly blackened on all sides. (Alternatively, roast your pepper over an open flame on a grill or gas stovetop until tender and charred on all sides — about 5 minutes). Then wrap in foil to steam for a few minutes (this will help the skin come off more easily).
In the meantime, toast almonds over medium-low heat in a dry skillet, stirring frequently, being careful not to burn. Toast until light golden brown — about 3-5 minutes. Set aside.
Unwrap bell peppers and carefully remove charred skin, stems, and seeds (be careful as they’ll still be hot). Then add to a small food processor or blender along with toasted almonds, olive oil, lemon juice, garlic, salt, and chili flake.
Either blend until creamy and smooth, or pulse / blend for a few seconds for a chunkier texture. We like a texture that's somewhere in between: mostly creamy with a few bits of almonds and garlic intact.
Add more olive oil or water to make it creamier. Taste and adjust flavor as needed, adding more lemon for acidity, garlic for zing, salt to taste, or chili flake for heat. We added a bit more of each.